"Unable to resolve action..." warning doesn't disappear after finishing edit

**Describe the bug**
Occasionally, when I edit a referenced action version, a warning about the non-existing version appears during editing and doesn't disappear after finishing the edit. For example, I changed the action from `slidoapp/xcresulttool@v2.0.0` to `slidoapp/xcresulttool@v3.1.0` by deleting "2.0" and replacing it with "3.1". However, the warning got stuck on "Unable to resolve action slidoapp/xcresulttool@v.0.0, repository or version not found." Even closing and reopening the workflow file didn't help, I had to restart VSCode to get rid of that warning message.

**To Reproduce**
Difficult to reproduce, it happens randomly while editing the referenced actions

**Expected behavior**
After finishing the edit, the plugin re-checks the existence of the final version of the action being edited (`v3.1.0`, not `v.0.0`).

**Screenshots**

**Extension Version**
`v0.27.0`

**Additional context**
Add any other context about the problem here.

No files or tests are named. Start by tracing the extension's action-reference validation and diagnostic refresh when a workflow action version is edited in place, then try reproducing the stale warning; done means the diagnostic reflects the final version without requiring a VS Code restart.

Written by the indexing model from the issue text.