[infra] Add configs for Python3 builder

No-Try: true
Bug: chromium:1256445
Change-Id: If028ec562fe10769e9a3a2dcdba9cf2074cd72a1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3417435
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Auto-Submit: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Liviu Rau <liviurau@chromium.org>
Commit-Queue: Liviu Rau <liviurau@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78783}

infra/mb/mb_config.pyl

@@ -116,6 +116,7 @@
       'V8 Linux64 - pointer compression - builder': 'release_x64_pointer_compression',
       'V8 Linux64 - pointer compression without dchecks':
           'release_x64_pointer_compression_without_dchecks',
+      'V8 Linux64 - python3 - builder': 'release_x64',
       'V8 Linux64 - arm64 - sim - pointer compression - builder':
           'release_simulate_arm64_pointer_compression',
       'V8 Linux64 gcc - debug builder': 'debug_x64_gcc',

infra/testing/builders.pyl

@@ -1360,6 +1360,14 @@
       {'name': 'v8testing', 'shards': 2},
     ],
   },
+  'V8 Linux64 - python3': {
+    'swarming_dimensions' : {
+      'os': 'Ubuntu-18.04',
+    },
+    'tests': [
+      {'name': 'v8testing', 'shards': 2},
+    ],
+  },
   'V8 Linux64 - shared': {
     'swarming_dimensions' : {
       'os': 'Ubuntu-18.04',