[TASK] Use TYPO3 12.4 for TYPO3 12

TYPO3 12.4 AKA 12LTS has been released.

Author: oliverklee

.github/workflows/tests.yml

@@ -42,16 +42,16 @@ jobs:
           - typo3-version: "^11.5"
             php-version: "8.2"
             composer-flags: " --prefer-lowest"
-          - typo3-version: "^12.3"
+          - typo3-version: "^12.4"
             php-version: "8.1"
             composer-flags: ""
-          - typo3-version: "^12.3"
+          - typo3-version: "^12.4"
             php-version: "8.1"
             composer-flags: " --prefer-lowest"
-          - typo3-version: "^12.3"
+          - typo3-version: "^12.4"
             php-version: "8.2"
             composer-flags: ""
-          - typo3-version: "^12.3"
+          - typo3-version: "^12.4"
             php-version: "8.2"
             composer-flags: " --prefer-lowest"