Fix the configuration path in the GitHub Actions workflow for the Flu…

…ent linter

I noticed the following warning in the GitHub Actions workflow logs:

`Configuration file not found: .github/linter_config.yml`

The configuration file is called `fluent_linter_config.yml` instead, so
this commit fixes the path so it points to the correct file.

Fixes 487816b.

.github/workflows/fluent_linter.yml

@@ -39,4 +39,4 @@ jobs:
 
       - name: Lint Fluent reference files
         run: |
-          moz-fluent-lint ./l10n/en-US --config .github/linter_config.yml
+          moz-fluent-lint ./l10n/en-US --config .github/fluent_linter_config.yml