patman: Correct a stray quote

A quote character was added a few years ago, but was not intended. Drop
it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/func_test.py b/tools/patman/func_test.py
index a31c950..161b5ad 100644
--- a/tools/patman/func_test.py
+++ b/tools/patman/func_test.py
@@ -152,7 +152,7 @@
             Commit-changes: 2
             - Changes only for this commit
 
-'            Cover-changes: 4
+            Cover-changes: 4
             - Some notes for the cover letter
 
             Cover-letter: