tests: fix formatting of test file

Author: Bushuo

rewatch/testrepo/packages/deprecated-config/src/Main.res

@@ -1,2 +1,2 @@
 let x = 1
-let y = 1
+let y = 1

rewatch/tests/format.sh

@@ -12,6 +12,7 @@ then
     git restore .
 else
     error "Error formatting test package"
+    echo "Expected 4 files to be changed, got $git_diff_file_count"
     echo $error_output
     exit 1
 fi