docs: fix grammar in action.yml

[iheziececil3-byte]

Summary

• Fixed a grammatical issue in action.yml by adding the missing article in the upload-sarif description.
• No functional behavior was changed.

Validation

• git diff --check passed.
• make lint could not be run because GNU Make is not installed in the local Windows environment.
• cargo test --workspace could not be run because Rust/Cargo is not installed in the local environment.

Closes #1345

[vercel]

@iheziececil3-byte is attempting to deploy a commit to the gbangbolaoluwagbemiga's projects Team on Vercel.

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