GH Actions: pin re-usable workflows too

Follow up on 6, which added commit hash pinning to all externally managed action runners, this commit now also adds this to the re-usable workflows managed in the `PHPCSStandards/.github` repository.

Author: jrfnl

.github/workflows/qa.yml

@@ -58,10 +58,10 @@ jobs:
         run: cs2pr ./phpcs-report.xml
 
   phpstan:
-    uses: PHPCSStandards/.github/.github/workflows/reusable-phpstan.yml@main
+    uses: PHPCSStandards/.github/.github/workflows/reusable-phpstan.yml@9d51cbe2ff0bde5f7f5b2cf7608e9e13d593c6f2 # v1.0.0
 
   yamllint:
     name: 'Lint Yaml'
-    uses: PHPCSStandards/.github/.github/workflows/reusable-yamllint.yml@main
+    uses: PHPCSStandards/.github/.github/workflows/reusable-yamllint.yml@9d51cbe2ff0bde5f7f5b2cf7608e9e13d593c6f2 # v1.0.0
     with:
       strict: true