Update the linting workflow on GitHub (#8405)

* Delete main.yml

Removing the Markdown lint test as a duplicate of the Lint Code Base test

* Update linter.yml

Run linters on any pull request, not only to master or develop

Author: dshevtsov

.github/workflows/linter.yml

@@ -11,14 +11,11 @@ name: Lint Code Base
 # https://help.github.com/en/articles/workflow-syntax-for-github-actions
 #
 
-#############################
-# Start the job on all push #
-#############################
+###################################
+# Start the job on a pull request #
+###################################
 on:
-  pull_request:
-    branches:
-      - master
-      - 2.*-develop
+  pull_request
 
 ###############
 # Set the Job #