fix(pr-validation): remove sudo from shellcheck install

The act runner container runs as root and does not have sudo
installed, causing CI job 187 to fail with "sudo: command not found".

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

.github/workflows/pr-validation.yaml

@@ -34,7 +34,7 @@ jobs:
 
       - name: Install shellcheck
         run: |
-          sudo apt-get update -qq && sudo apt-get install -y -qq shellcheck >/dev/null 2>&1
+          apt-get update -qq && apt-get install -y -qq shellcheck >/dev/null 2>&1
 
       - name: Shellcheck scripts
         run: |