ci: expand ci matrix to test more LLVM versions

[wmmc88]

This pull request updates the supported LLVM versions across all GitHub Actions workflows and clarifies the documentation regarding compatible LLVM versions. The main focus is to ensure broader compatibility and clearer guidance for contributors using LLVM with the project.

Updates to supported LLVM versions in CI workflows:

• Added LLVM versions 19.1.7, 20.1.8, and 21.1.2 to the llvm matrix in the following workflow files to expand CI testing coverage:
  • .github/workflows/build.yaml
  • .github/workflows/codeql.yaml
  • .github/workflows/docs.yaml
  • .github/workflows/lint.yaml
  • .github/workflows/local-development-makefile.yaml
  • .github/workflows/test.yaml

Documentation improvements:

• Updated the README.md to reference the list of tested/supported LLVM versions in the CI workflow, helping users identify which LLVM versions are compatible with the project.This pull request updates the project's CI workflows to test against a broader range of LLVM versions, ensuring compatibility with newer LLVM releases. It also updates the documentation to point to the list of supported LLVM versions in the CI configuration.

CI workflow updates:

• Added LLVM versions 18.1.8, 19.1.1, 20.1.0, and 21.1.0 to the matrix in .github/workflows/build.yaml, .github/workflows/test.yaml, .github/workflows/lint.yaml, .github/workflows/docs.yaml, .github/workflows/codeql.yaml, and .github/workflows/local-development-makefile.yaml to expand version coverage in CI. [1] [2] [3] [4] [5] [6]

Documentation update:

• Updated the README.md to reference the list of tested/supported LLVM versions in the CI workflow configuration for easier discovery and clarity.

[Copilot]

Pull request overview

This PR expands the CI testing matrix to include additional LLVM versions (18.1.8, 19.1.1, 20.1.0, and 21.1.0) across all GitHub Actions workflows, and updates the README documentation to reference the CI configuration for supported LLVM versions.

Key changes:

• Added four new LLVM versions (18.1.8, 19.1.1, 20.1.0, 21.1.0) to the test matrix in six CI workflow files
• Updated README.md to link to the CI workflow configuration for the list of tested/supported LLVM versions

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
.github/workflows/build.yaml	Added LLVM versions 18.1.8, 19.1.1, 20.1.0, and 21.1.0 to the build workflow matrix
.github/workflows/test.yaml	Added LLVM versions 18.1.8, 19.1.1, 20.1.0, and 21.1.0 to the test workflow matrix
.github/workflows/lint.yaml	Added LLVM versions 18.1.8, 19.1.1, 20.1.0, and 21.1.0 to the lint workflow matrix
.github/workflows/docs.yaml	Added LLVM versions 18.1.8, 19.1.1, 20.1.0, and 21.1.0 to the docs workflow matrix
.github/workflows/codeql.yaml	Added LLVM versions 18.1.8, 19.1.1, 20.1.0, and 21.1.0 to the CodeQL workflow matrix
.github/workflows/local-development-makefile.yaml	Added LLVM versions 18.1.8, 19.1.1, 20.1.0, and 21.1.0 to the local development workflow matrix
README.md	Added reference to CI workflow configuration for list of tested/supported LLVM versions

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.67%. Comparing base (723a4eb) to head (8ceb042).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #593   +/-   ##
=======================================
  Coverage   82.67%   82.67%           
=======================================
  Files          25       25           
  Lines        7135     7135           
  Branches     7135     7135           
=======================================
  Hits         5899     5899           
  Misses       1107     1107           
  Partials      129      129           

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[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 9 comments.

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[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

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[Copilot]

The LLVM versions added here (19.1.7, 20.1.8, 21.1.2) differ from those mentioned in the PR description (18.1.8, 19.1.1, 20.1.0, 21.1.0). The PR description states that versions 18.1.8, 19.1.1, 20.1.0, and 21.1.0 would be added, but the actual code adds 19.1.7, 20.1.8, and 21.1.2 instead. Additionally, LLVM 18 is completely omitted, which may be intentional given the README.md mentions a bug in LLVM 18 for ARM64, but this should be clarified. Please ensure the PR description accurately reflects the actual changes made.

Suggested change

	- 19.1.7
	- 20.1.8
	- 21.1.2
	# 18.1.8 is omitted due to a known bug in LLVM 18 for ARM64 (see README.md)
	- 19.1.1
	- 20.1.0
	- 21.1.0