chore: Drop PHP 8.1 support

Author: LeSuisse

.github/workflows/CI.yml

@@ -19,7 +19,7 @@ jobs:
           - 6379/tcp
     strategy:
       matrix:
-        php: ['8.1', '8.2', '8.3', '8.4']
+        php: ['8.2', '8.3', '8.4']
         dependencies: ['--ignore-platform-req=php', '--prefer-lowest --prefer-stable --ignore-platform-req=php']
     steps:
       - name: Checkout

composer.json

@@ -3,7 +3,7 @@
     "description": "Prometheus instrumentation library",
     "license": "Apache-2.0",
     "require": {
-        "php": "~8.1.0|~8.2.0|~8.3.0|~8.4.0",
+        "php": "~8.2.0|~8.3.0|~8.4.0",
         "ext-json": "*",
         "psr/http-client": "^1.0",
         "psr/http-factory": "^1.0",