ARM64 parallel builds (#40868)

Author: lithomas1

.travis.yml

@@ -35,16 +35,9 @@ matrix:
   fast_finish: true
 
   include:
-    - arch: arm64
+    - arch: arm64-graviton2
       env:
-        - JOB="3.7, arm64" PYTEST_WORKERS=1 ENV_FILE="ci/deps/travis-37-arm64.yaml" PATTERN="(not slow and not network and not clipboard and not arm_slow)"
-
-  allow_failures:
-    # Moved to allowed_failures 2020-09-29 due to timeouts https://github.com/pandas-dev/pandas/issues/36719
-    - arch: arm64
-      env:
-        - JOB="3.7, arm64" PYTEST_WORKERS=1 ENV_FILE="ci/deps/travis-37-arm64.yaml" PATTERN="(not slow and not network and not clipboard and not arm_slow)"
-
+        - JOB="3.7, arm64" PYTEST_WORKERS="auto" ENV_FILE="ci/deps/travis-37-arm64.yaml" PATTERN="(not slow and not network and not clipboard and not arm_slow)"
 
 before_install:
   - echo "before_install"