Fix exclusion of Dependabot commit message checks (#43)

Need brackets to group the expressions properly

Author: johnboyes

.github/workflows/check-commit-message.yml

@@ -11,7 +11,7 @@ on:  # yamllint disable-line rule:truthy
 
 jobs:
   check-commit-message-style:
-    if: github.actor!= 'dependabot[bot]' && contains(github.head_ref, 'dependabot/github_actions/') == false
+    if: (github.actor!= 'dependabot[bot]') && (contains(github.head_ref, 'dependabot/github_actions/') == false)
     name: Check commit message style
     runs-on: ubuntu-latest
     steps: