Merge pull request #46 from Certora/oz/ci

Change ci triggers

Author: chandrakananandi

.github/workflows/gambit.yml

@@ -1,6 +1,15 @@
 name: Gambit
 
-on: [push, pull_request]
+on:
+  push:
+    branches:
+      - master
+    tags: 
+      - 'v*'
+  pull_request:
+    branches:
+      - master
+  workflow_dispatch:
 
 env:
   CARGO_TERM_COLOR: always