drop older php version support

Author: nhalstead

.github/workflows/run-tests.yml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: [7.3, 7.4, 8.0, 8.1, 8.2, 8.3]
+        php: [8.1, 8.2, 8.3]
         dependency-version: [prefer-lowest, prefer-stable]
 
     name: PHP ${{ matrix.php }} - ${{ matrix.dependency-version }}