CI: try running even PHP 7.4

Author: janedbal

.github/workflows/platform-matrix-test.yml renamed to .github/workflows/platform-test.yml

@@ -1,6 +1,6 @@
 # https://help.github.com/en/categories/automating-your-workflow-with-github-actions
 
-name: "Platform matrix test"
+name: "Platform test"
 
 on:
   pull_request:
@@ -10,7 +10,7 @@ on:
 
 jobs:
   tests:
-    name: "Platform matrix test"
+    name: "Platform test"
     runs-on: "ubuntu-latest"
     env:
       MYSQL_HOST: '127.0.0.1'
@@ -21,6 +21,7 @@ jobs:
       fail-fast: false
       matrix:
         php-version:
+          - "7.4"
           - "8.0"
           - "8.1"
           - "8.2"