chore: update go lang used in Dockerfile to v1.26.2

[jvanz]

Description

Updates the Go lang version used in Dockerfiles to v1.26.2.

Warning

I'm not updating go lang in other places because there is the PR #1631 which is doing that.

[Copilot]

Pull request overview

Updates the Go toolchain version used for building project binaries inside Docker images, aligning the build containers with the newer Go patch release (while other Go-version alignment is handled in #1631).

Changes:

• Bump golang builder image from 1.26.1 to 1.26.2 (with updated pinned digest) for the controller build.
• Bump golang builder image from 1.26.1 to 1.26.2 (with updated pinned digest) for the audit-scanner build.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
Dockerfile.kubewarden-controller	Updates the Go builder base image to golang:1.26.2 (pinned by digest).
Dockerfile.audit-scanner	Updates the Go builder base image to golang:1.26.2 (pinned by digest).

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.40%. Comparing base (2a6b879) to head (9033842).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1643      +/-   ##
==========================================
- Coverage   80.48%   80.40%   -0.08%     
==========================================
  Files         127      127              
  Lines       16411    16411              
==========================================
- Hits        13209    13196      -13     
- Misses       3202     3215      +13     

Flag	Coverage Δ
rust-tests	80.40% <ø> (-0.08%)	⬇️

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