Fix typo in readme (#66)

diff --git a/pkgs/firehose/README.md b/pkgs/firehose/README.md
index 7374dc1..8c5263b 100644
--- a/pkgs/firehose/README.md
+++ b/pkgs/firehose/README.md
@@ -74,7 +74,7 @@
 
 jobs:
   publish:
-    uses: dart-lang/ecosystem/.github/workflows/publish.yml@main
+    uses: dart-lang/ecosystem/.github/workflows/publish.yaml@main
 ```
 
 ## Workflow docs