removing solana_main_trigger_PR.yml

require some more modification to migrate from travis ci to github actions

.github/workflows/solana_main_trigger_PR.yml

@@ -1,12 +0,0 @@
-name : solana_main
-on:
-  pull_request:
-    branches:  [master]
-    tags : /^v\d+\.\d+/
-    paths-ignore:
-      - 'docs/**'
-jobs:
- solana_main_trigger:
-    runs-on: windows-latest
-    steps:
-      - run: echo "Triggering solana_main on PR"