adjust to semantic branch naming

.github/ISSUE_TEMPLATE.md

@@ -39,5 +39,5 @@ $ composer show --latest 'symfony-cmf/*'
     If it's an error message or piece of code, use code block tags,
     and make sure you provide the whole stack trace(s),
     not just the first error message you can see.
-    More details here: https://github.com/symfony-cmf/core-bundle/blob/master/CONTRIBUTING.md#issues
+    More details here: https://github.com/symfony-cmf/core-bundle/blob/3.x/CONTRIBUTING.md#issues
 -->

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,6 +1,6 @@
 | Q             | A
 | ------------- | ---
-| Branch?       | "master" for new features / the branch of the current release for fixes
+| Branch?       | 3.x for new features / the branch of the current release for fixes
 | Bug fix?      | yes/no
 | New feature?  | yes/no
 | BC breaks?    | yes/no

.github/workflows/test-application.yaml

@@ -4,7 +4,6 @@ on:
     pull_request:
     push:
         branches:
-            - 'master'
             - '[0-9]+.x'
             - '[0-9]+.[0-9]+'
             - '[0-9]+.[0-9]+.x'

composer.json

@@ -56,11 +56,5 @@
         "psr-4": {
             "Symfony\\Cmf\\Bundle\\CoreBundle\\Tests\\": "tests/"
         }
-    },
-    "extra": {
-        "branch-alias": {
-            "dev-master": "3.x-dev"
-        }
-    },
-    "minimum-stability": "dev"
+    }
 }