Fix gpg verification command (#13035)

(cherry picked from commit 825e9cb)

dev/README_RELEASE_AIRFLOW.md

@@ -379,7 +379,7 @@ Once you have the keys, the signatures can be verified by running this:
 ```shell script
 for i in *.asc
 do
-   echo "Checking $i"; gpg --verify `basename $i .asc`
+   echo "Checking $i"; gpg --verify $i
 done
 ```