Update kani.yml (rust-lang#1592)

Don't ignore development branches. Ignore tags only.

Author: celinval

.github/workflows/kani.yml

@@ -6,8 +6,8 @@ on:
   push:
     # Not just any push, as that includes tags.
     # We don't want to re-trigger this workflow when tagging an existing commit.
-    branches:
-      - main
+    tags-ignore:
+      - '**'
 
 env:
   RUST_BACKTRACE: 1