Created contributing.md and modify gh actions scripts

.github/PULL_REQUEST_TEMPLATE.md

@@ -15,4 +15,4 @@ You can do so here: https://github.com/IntellectualSites/FastAsyncWorldEdit-1.13
 - [] I included all information required in the sections above
 - [] I tested my changes and approved their functionality
 - [] I ensured my changes do not break other parts of the code
-- [] I read and followed the [contribution guidelines](https://github.com/IntellectualSites/FastAsyncWorldEdit-1.13/blob/breaking/CONTRIBUTING.md)
+- [] I read and followed the [contribution guidelines](https://github.com/IntellectualSites/FastAsyncWorldEdit-1.13/blob/1.15/CONTRIBUTING.md)

.github/workflows/gradle.yml

@@ -3,13 +3,9 @@ name: Java CI
 on:
   push:
     branches:
-    - master
-    - merge
     - 1.15
   pull_request:
     branches:
-    - master
-    - merge
     - 1.15
  
 jobs: