autoroll: Update Clang script path.

tools/clang/scripts/update.sh was deleted in
https://chromium.googlesource.com/chromium/src/+/656a6433abb41ba076c337b9ffb8c8899c3f20b7
so now the update.py is used on all platforms.
Update our autoroll script accordingly.

NOTRY=True

Review URL: https://codereview.webrtc.org/1493683003

Cr-Commit-Position: refs/heads/master@{#10879}
diff --git a/tools/autoroller/roll_chromium_revision.py b/tools/autoroller/roll_chromium_revision.py
index 0d5d03b..56d878a 100755
--- a/tools/autoroller/roll_chromium_revision.py
+++ b/tools/autoroller/roll_chromium_revision.py
@@ -43,9 +43,9 @@
 find_depot_tools.add_depot_tools_to_path()
 from gclient import GClientKeywords
 
-CLANG_UPDATE_SCRIPT_URL_PATH = 'tools/clang/scripts/update.sh'
+CLANG_UPDATE_SCRIPT_URL_PATH = 'tools/clang/scripts/update.py'
 CLANG_UPDATE_SCRIPT_LOCAL_PATH = os.path.join('tools', 'clang', 'scripts',
-                                              'update.sh')
+                                              'update.py')
 
 DepsEntry = collections.namedtuple('DepsEntry', 'path url revision')
 ChangedDep = collections.namedtuple('ChangedDep',