Upgraded monolog/monolog and psr/container, switched to PHP 8.1.x

Note: our `Dockerfile` already runs on PHP 8.1.x, so this is just aligning
`composer.json` with our declared package versions

composer.json

@@ -4,7 +4,7 @@
     "description": "Application that eases release management in the Laminas organisation through GitHub actions",
     "license": "BSD-3-Clause",
     "require": {
-        "php": "^8.0.0",
+        "php": "~8.1.0",
         "azjezz/psl": "^1.8.1",
         "jwage/changelog-generator": "^1.3.0",
         "laminas/laminas-diactoros": "^2.5.0",
@@ -17,7 +17,7 @@
         "php-http/httplug": "^2.2.0",
         "psr/http-client": "^1.0.1",
         "psr/http-message": "^1.0.1",
-        "psr/log": "^1.1.3",
+        "psr/log": "^2.0.0",
         "symfony/console": "^5.2.3"
     },
     "require-dev": {
@@ -32,7 +32,7 @@
     "config": {
         "sort-packages": true,
         "platform": {
-            "php": "8.0.99"
+            "php": "8.1.99"
         },
         "allow-plugins": {
             "infection/extension-installer": true,