Merge pull request teamviewer#6 from teamviewer/danieljoos-patch-1

Update .travis.yml

Author: danieljoos

.travis.yml

@@ -4,17 +4,17 @@ services:
   - docker
 
 install:
-  - docker pull microsoft/powershell:6.0.4-ubuntu-trusty
+  - docker pull mcr.microsoft.com/powershell:6.2.3-alpine-3.8
 
 script:
   # Unit Tests for PowerShell scripts
-  - docker run -v ${TRAVIS_BUILD_DIR}:/tmp/src/ microsoft/powershell:6.0.4-ubuntu-trusty pwsh -c "
+  - docker run -v ${TRAVIS_BUILD_DIR}:/tmp/src/ mcr.microsoft.com/powershell:6.2.3-alpine-3.8 pwsh -c "
       \$ProgressPreference='SilentlyContinue';
       Install-Module Pester -Force -SkipPublisherCheck -Scope CurrentUser;
       Invoke-Pester /tmp/src;
       exit $LastExitCode;"
   # Linting for PowerShell scripts
-  - docker run -v ${TRAVIS_BUILD_DIR}:/tmp/src/ microsoft/powershell:6.0.4-ubuntu-trusty pwsh -c "
+  - docker run -v ${TRAVIS_BUILD_DIR}:/tmp/src/ mcr.microsoft.com/powershell:6.2.3-alpine-3.8 pwsh -c "
       \$ProgressPreference='SilentlyContinue';
       Install-Module PSScriptAnalyzer -Force -SkipPublisherCheck -Scope CurrentUser;
       Invoke-ScriptAnalyzer -Path /tmp/src -Recurse -ReportSummary -EnableExit;