Update CI to only run platform tests on git push events

Author: Mordil

.gitlab/ci/main.yml

@@ -59,6 +59,8 @@ Code Climate:
       codequality: gl-code-quality-report.json
 
 .standard-platform-test:
+  rules:
+    - if: $CI_PIPELINE_SOURCE == "push"
   stage: Platform Tests
   trigger:
     strategy: depend

.gitlab/ci/platform-test.yml

@@ -15,9 +15,3 @@ stages:
   script:
     - swift build --build-tests --enable-test-discovery --sanitize=thread -v 
     - swift test --skip-build
-  only:
-    - branches
-    - tags
-  except:
-    - schedules
-