travis: ignore failed brew upgrade npm, update xcode

PR-URL: #1932
Reviewed-By: Rod Vagg <[email protected]>

Author: cclauss

.travis.yml

@@ -8,7 +8,7 @@ matrix:
       python: 2.7
     - name: "Python 2.7 on macOS"
       os: osx
-      osx_image: xcode11
+      osx_image: xcode11.2
       language: shell  # 'language: python' is not yet supported on macOS
       env: NODE_GYP_FORCE_PYTHON=python2
       before_install: HOMEBREW_NO_AUTO_UPDATE=1 brew install npm
@@ -57,10 +57,10 @@ matrix:
 
     - name: "Python 3.7 on macOS"
       os: osx
-      #osx_image: xcode11
+      osx_image: xcode11.2
       language: shell  # 'language: python' is not yet supported on macOS
       env: NODE_GYP_FORCE_PYTHON=python3
-      before_install: HOMEBREW_NO_AUTO_UPDATE=1 brew install npm
+      before_install: HOMEBREW_NO_AUTO_UPDATE=1 brew upgrade npm || true
     - name: "Node.js 12 & Python 3.7 on Windows"
       os: windows
       language: node_js