Rework MariaDB tests to run on last PHP 7 version

- the last PHP 7 version is 7.4 and this is the version readily
  install-able on Rocky8, so test against that rather than
  versions 7.0 or 7.1.
- this involves supplying seperate composer.json/lock files
  to run different versions of Doctrine, as there is no version
  that supports both php 5.4 and 7.4.

.github/workflows/continuous-integration.yml

@@ -67,29 +67,19 @@ jobs:
         # Define jobs for all combinations of php, mariadb and extension, up to "include"
         # Tests will be performed for each combination
         # These can fail if "experimental" is true. Currently all must pass
-        php-version: ["5.4", "5.5", "5.6", "7.0", "7.1"]
+        php-version: ["5.4", "5.5", "5.6", "7.4"]
         mariadb-version: ["10.3"]
         extension: ["pdo_mysql"]
         experimental: [false]
         include:
-          # Define jobs for individual combinations to be tested
-          # These can fail if "experimental" is true. Currently all can fail
-          - php-version: "7.2"
-            mariadb-version: "10.3"
-            extension: "pdo_mysql"
-            experimental: true
-          - php-version: "7.3"
-            mariadb-version: "10.3"
-            extension: "pdo_mysql"
-            experimental: true
+          - php-version: "5.4"
+            composer-json: "composer.json"
+          - php-version: "5.5"
+            composer-json: "composer.json"
+          - php-version: "5.6"
+            composer-json: "composer.json"
           - php-version: "7.4"
-            mariadb-version: "10.3"
-            extension: "pdo_mysql"
-            experimental: true
-          - php-version: "8.0"
-            mariadb-version: "10.3"
-            extension: "pdo_mysql"
-            experimental: true
+            composer-json: "composer-7.4.json"
 
     services:
       mariadb:
@@ -130,6 +120,8 @@ jobs:
             ${{ runner.os }}-php-
 
       - name: Install dependencies
+        env:
+          COMPOSER: ${{ matrix.composer-json }}
         run: composer install --no-progress
 
       - name: Set up unit testing

composer-7.4.json

@@ -0,0 +1,15 @@
+{
+    "name": "stfc-egi/gocdb",
+    "description": "A web portal and REST style API for e-Infrastructure topology managment",
+    "require": {
+	"doctrine/orm": "2.6.*"
+    },
+    "require-dev": {
+        "phpunit/phpunit": "4.8.*",
+        "phpunit/dbunit": ">=1.2",
+        "phpmd/phpmd": "^2.13",
+        "squizlabs/php_codesniffer": "^3.7",
+        "taq/pdooci": "^1.0"
+
+    }
+}