GH Actions: minor simplification

... of the bash `date` command in the earlier pulled cache busting.

Author: jrfnl

.github/workflows/cs.yml

@@ -50,8 +50,8 @@ jobs:
       - name: Install Composer dependencies
         uses: "ramsey/composer-install@v2"
         with:
-          # Bust the cache at least once a month - output format: YYYY-MM-DD.
-          custom-cache-suffix: $(date -u -d "-0 month -$(($(date +%d)-1)) days" "+%F")
+          # Bust the cache at least once a month - output format: YYYY-MM.
+          custom-cache-suffix: $(date -u "+%Y-%m")
 
       # @link http://xmlsoft.org/xmllint.html
       - name: Install xmllint

.github/workflows/quicktest.yml

@@ -73,8 +73,8 @@ jobs:
       - name: Install Composer dependencies
         uses: "ramsey/composer-install@v2"
         with:
-          # Bust the cache at least once a month - output format: YYYY-MM-DD.
-          custom-cache-suffix: $(date -u -d "-0 month -$(($(date +%d)-1)) days" "+%F")
+          # Bust the cache at least once a month - output format: YYYY-MM.
+          custom-cache-suffix: $(date -u "+%Y-%m")
 
       - name: Lint against parse errors (PHP 7.2+)
         if: ${{ matrix.phpcs_version == 'dev-master' && matrix.php >= '7.2' }}

.github/workflows/test.yml

@@ -107,16 +107,16 @@ jobs:
         if: ${{ matrix.php < 8.2 }}
         uses: "ramsey/composer-install@v2"
         with:
-          # Bust the cache at least once a month - output format: YYYY-MM-DD.
-          custom-cache-suffix: $(date -u -d "-0 month -$(($(date +%d)-1)) days" "+%F")
+          # Bust the cache at least once a month - output format: YYYY-MM.
+          custom-cache-suffix: $(date -u "+%Y-%m")
 
       # For PHP "nightly", we need to install with ignore platform reqs as not all dependencies allow installation.
       - name: Install Composer dependencies - with ignore platform
         if: ${{ matrix.php >= 8.2 }}
         uses: "ramsey/composer-install@v2"
         with:
           composer-options: --ignore-platform-reqs
-          custom-cache-suffix: $(date -u -d "-0 month -$(($(date +%d)-1)) days" "+%F")
+          custom-cache-suffix: $(date -u "+%Y-%m")
 
       - name: Lint against parse errors (PHP 7.2+)
         if: ${{ matrix.phpcs_version == 'dev-master' && matrix.php >= '7.2' }}