feat(ci): only on push

.github/workflows/build_and_test.yml

@@ -4,7 +4,7 @@ on:
   pull_request:
     types: [opened, reopened, synchronize]
     branches:
-      - '**'
+      - "**"
 
 jobs:
   prepare-rskj:
@@ -90,16 +90,16 @@ jobs:
       - name: If GH event is PR
         if: github.event_name == 'pull_request'
         run: |
-          git branch -f master origin/master
-          pr_number==${{ github.event.pull_request.number }}
-          extra_flags="-Dsonar.pullrequest.base=master
-            -Dsonar.pullrequest.branch=${{ github.head_ref }}
-            -Dsonar.pullrequest.key=$pr_number"
+          pr_number=${{ github.event.pull_request.number }}
+          extra_flags="-Dsonar.pullrequest.base=${{ github.base_ref }} \
+          -Dsonar.pullrequest.branch=${{ github.head_ref }} \
+          -Dsonar.pullrequest.key=$pr_number"
+      
           ./gradlew sonarqube --no-daemon -x build -x test \
-            $extra_flags \
-            -Dsonar.organization=rsksmart \
-            -Dsonar.host.url="https://sonarcloud.io" \
-            -Dsonar.token="${{ secrets.SONAR_TOKEN }}"
+          $extra_flags \
+          -Dsonar.organization=rsksmart \
+          -Dsonar.host.url="https://sonarcloud.io" \
+          -Dsonar.token="${{ secrets.SONAR_TOKEN }}"
 
       - name: If not
         if: github.event_name != 'pull_request'