[DEPS] switch download.py hook back to python

download.py became flaky after switching to vpython
and causing build breakages. Switch it back to
python.

[email protected]

Bug: 784243
Change-Id: Ie0ca441bc0c9485c4052251a8e4c757697cbc7e7
No-Try: true
No-Presubmit: true
Reviewed-on: https://chromium-review.googlesource.com/769230
Commit-Queue: Nodir Turakulov <[email protected]>
Reviewed-by: Nodir Turakulov <[email protected]>
Cr-Commit-Position: refs/heads/master@{#516364}

Author: nodirt

DEPS

@@ -774,7 +774,7 @@ hooks = [
     'pattern': 'src/third_party/binutils',
     'condition': 'host_os == "linux"',
     'action': [
-        'vpython',
+        'python',
         'src/third_party/binutils/download.py',
     ],
   },