fix: install actionlint to user-writable path

The runner doesn't have write access to /usr/local/bin. Install to
$HOME/.local/bin instead and add it to GITHUB_PATH.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

.github/workflows/pr-validation.yaml

@@ -16,8 +16,10 @@ jobs:
       - name: Install actionlint
         run: |
           ACTIONLINT_VERSION="1.7.7"
+          mkdir -p "$HOME/.local/bin"
           curl -fsSL "https://github.com/rhysd/actionlint/releases/download/v${ACTIONLINT_VERSION}/actionlint_${ACTIONLINT_VERSION}_linux_amd64.tar.gz" \
-            | tar -xz -C /usr/local/bin actionlint
+            | tar -xz -C "$HOME/.local/bin" actionlint
+          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
 
       - name: Validate workflow YAML with actionlint
         run: actionlint -color .github/workflows/*.yaml