Fix typo "runs-un" in GHA workflows (Case 171395)

Author: mpdude

.github/workflows/dependencies.yml

@@ -12,7 +12,7 @@ env:
 jobs:
     composer-require-checker:
         name: Check missing composer requirements
-        runs-un: ubuntu-22.04
+        runs-on: ubuntu-22.04
         steps:
             -   uses: actions/checkout@v4
             -   name: Konfiguriere PHP-Version und -Einstellungen im Worker-Node

.github/workflows/fix-cs-php.yml

@@ -12,7 +12,7 @@ name: Coding Standards
 jobs:
     open-pr-for-cs-violations:
         name: PHP-CS-Fixer
-        runs-un: ubuntu-22.04
+        runs-on: ubuntu-22.04
         if: github.actor != 'dependabot[bot]'
         steps:
             -   name: Checkout code

.github/workflows/tests.yml

@@ -13,7 +13,7 @@ env:
 jobs:
     PHPUnit:
         name: PHPUnit
-        runs-un: ubuntu-22.04
+        runs-on: ubuntu-22.04
         steps:
             -   uses: actions/checkout@v4
             -   run: mkdir --mode=777 -p $GITHUB_WORKSPACE/{tmp,logs}