Force --no-progress on fsck runs

Looks like verify_commit_graph is outputting progress info even when not
running in a terminal, so force --no-progress to quiet it down (and
report a bug).

Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
diff --git a/grokmirror/fsck.py b/grokmirror/fsck.py
index 73ccd78..769a135 100755
--- a/grokmirror/fsck.py
+++ b/grokmirror/fsck.py
@@ -262,7 +262,7 @@
 
 
 def run_git_fsck(fullpath, config, conn_only=False):
-    args = ['fsck', '--no-dangling', '--no-reflogs']
+    args = ['fsck', '--no-progress', '--no-dangling', '--no-reflogs']
     if conn_only:
         args.append('--connectivity-only')
         logger.info('   fsck : running with --connectivity-only')