bisect-kit: fix pylint warnings

depot_tools' pylint uprev to 2.6

BUG=None
TEST=pylint

Change-Id: Ia1b8dfb6304de60d7235d86abf4ba728252fd56d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/bisect-kit/+/2557857
Tested-by: Kuang-che Wu <kcwu@chromium.org>
Auto-Submit: Kuang-che Wu <kcwu@chromium.org>
Commit-Queue: Zheng-Jie Chang <zjchang@chromium.org>
Reviewed-by: Zheng-Jie Chang <zjchang@chromium.org>
diff --git a/bisect_kit/codechange.py b/bisect_kit/codechange.py
index dbc1b27..2c97423 100644
--- a/bisect_kit/codechange.py
+++ b/bisect_kit/codechange.py
@@ -348,7 +348,7 @@
   """
 
   def __init__(self, timestamp, path, repo_url, rev):
-    super(GitCheckoutCommit, self).__init__(timestamp, path)
+    super().__init__(timestamp, path)
     self.repo_url = repo_url
     self.rev = rev
 
@@ -379,7 +379,7 @@
   """
 
   def __init__(self, timestamp, path, repo_url, rev):
-    super(GitAddRepo, self).__init__(timestamp, path)
+    super().__init__(timestamp, path)
     self.repo_url = repo_url
     self.rev = rev