updated .travis.yml

.travis.yml

@@ -30,6 +30,10 @@ python:
   - "pypy"   # currently Python 2.7.13, PyPy 7.1.1
   - "pypy3"  # currently Python 3.6.1,  PyPy 7.1.1-beta0
 
+# https://docs.travis-ci.com/user/reference/osx/
+# macOS 10.15.7 - otherwise defaults to Mac macOS 10.13 with xcode9.4 otherwise - and HomeBrew update takes 50 minutes until the build times out :-/
+osx_image: xcode12.2
+
 matrix:
   fast_finish: true
   include:
@@ -71,7 +75,6 @@ matrix:
       language: python
       python: "pypy3"
 
-
 #   allow_failures:
 #     - python: "3.4"
 #     - python: "3.5"
@@ -81,8 +84,6 @@ matrix:
 #     - python: "pypy"
 #     - python: "pypy3"
 
-#dist: trusty
-
 sudo: required
 
 env: