Add missing fail-fast: false to workflow (#32)

Integration tests are flaky and in-progress jobs should not be cancelled
if one fails

Match
https://github.com/canonical/mysql-router-operators/blob/9e6811626937f7c5a67d90c06245e2a140adecf9/.github/workflows/integration_test_charm.yaml#L86

Author: carlcsaposs-canonical

.github/workflows/integration_test_charms.yaml

@@ -12,6 +12,7 @@ on:
 jobs:
   integration-test:
     strategy:
+      fail-fast: false
       matrix:
         path:
           - kubernetes