ci(e2e): uses latest npm version

Author: huafu

.travis.yml

@@ -14,5 +14,6 @@ node_js:
   - "6"
 
 script:
+  - npm -g install npm@latest
   - npm run clean -- --when-ci-commit-message
   - npm run test -- --coverage

appveyor.yml

@@ -18,7 +18,7 @@ install:
   # Typical npm stuff.
   - set CI=true
   - set TS_JEST_E2E_WORKDIR=%APPDATA%\ts-jest-e2e
-  - npm version
+  - npm -g install npm@latest
   - npm ci || npm install
   - npm run clean -- --when-ci-commit-message
 
@@ -34,4 +34,4 @@ test_script:
 build: off
 
 # Set build version format here instead of in the admin panel.
-version: "{build}"
+version: "{build}"