chore: remove outdated version tags from GitHub Actions (#457)

## Summary
- Removes version comment tags (e.g. `#v4`, `#v5`) from all GitHub
Actions workflow files
- These tags become incorrect when Dependabot updates the action SHAs
- The SHA pins are sufficient for version control

## Context
This addresses @domdomegg's comment in #453 about these tags becoming
outdated when using Dependabot. The SHAs already provide version
pinning, making the comment tags redundant and potentially misleading.

## Changes
- Removed version tags from all `uses:` statements in
`.github/workflows/*.yml`
- No functional changes to workflows

.github/workflows/ci.yml

@@ -13,15 +13,15 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout code
-      uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 #v4
+      uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8
 
     - name: Set up Go
-      uses: actions/setup-go@44694675825211faa026b3c33043df3e48a5fa00 #v5
+      uses: actions/setup-go@44694675825211faa026b3c33043df3e48a5fa00
       with:
         go-version-file: 'go.mod'
 
     - name: Cache Go modules
-      uses: actions/cache@0400d5f644dc74513175e3cd8d07132dd4860809 #v4
+      uses: actions/cache@0400d5f644dc74513175e3cd8d07132dd4860809
       with:
         path: |
           ~/.cache/go-build
@@ -57,15 +57,15 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout code
-      uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 #v4
+      uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8
 
     - name: Set up Go
-      uses: actions/setup-go@44694675825211faa026b3c33043df3e48a5fa00 #v5
+      uses: actions/setup-go@44694675825211faa026b3c33043df3e48a5fa00
       with:
         go-version-file: 'go.mod'
 
     - name: Cache Go modules
-      uses: actions/cache@0400d5f644dc74513175e3cd8d07132dd4860809 #v4
+      uses: actions/cache@0400d5f644dc74513175e3cd8d07132dd4860809
       with:
         path: |
           ~/.cache/go-build
@@ -81,7 +81,7 @@ jobs:
       run: make test-all
 
     - name: Upload coverage artifacts
-      uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 #v4
+      uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02
       with:
         name: coverage-report
         path: |