Soft drop PHP 5.X support, in favour of PHP 7.4

- This commit drops support for PHP 5.X, in favour of PHP 7.4
  support "out of the box".
- It is still possible to run GOCDB on PHP 5.X - however this
  will require specific deployments reverting this commit
  to restore the appropriate composer files.
- The `composer-5.4.{json, lock}` files will remain in the
  short term to facilitiate continued testing of the
  codebase against PHP 5.X. These files will be removed
  from the repository after 1st July 2024.
- NB: The diff rendered here is slightly weird.
  - it appears as a rename of the composer-7.4 files to the
    composer-5.4 files, which is not what has happened.
  - the pre-existing composer files were renamed to
    composer-5.4 files and then the composer-7.4 files
    were renamed to the composer files

Author: gregcorbett

.github/workflows/continuous-integration.yml

@@ -18,17 +18,17 @@ jobs:
         extension: ["pdo_mysql"]
         include:
           - php-version: "5.4"
-            composer-json: "composer.json"
+            composer-json: "composer-5.4.json"
           - php-version: "5.5"
-            composer-json: "composer.json"
+            composer-json: "composer-5.4.json"
           - php-version: "5.6"
-            composer-json: "composer.json"
+            composer-json: "composer-5.4.json"
           - php-version: "7.0"
-            composer-json: "composer.json"
+            composer-json: "composer-5.4.json"
           - php-version: "7.1"
-            composer-json: "composer.json"
+            composer-json: "composer-5.4.json"
           - php-version: "7.4"
-            composer-json: "composer-7.4.json"
+            composer-json: "composer.json"
 
     services:
       mariadb:

composer-7.4.json composer-5.4.json

@@ -2,7 +2,7 @@
     "name": "stfc-egi/gocdb",
     "description": "A web portal and REST style API for e-Infrastructure topology managment",
     "require": {
-	"doctrine/orm": "2.6.*"
+	"doctrine/orm": "2.5.14"
     },
     "require-dev": {
         "phpunit/phpunit": "4.8.*",