Remove Windows 1709 (EOL)

https://twitter.com/thaJeztah/status/1116392901267927041

Author: tianon

2.7/windows/windowsservercore-1709/Dockerfile

@@ -78,7 +78,7 @@ for version in "${versions[@]}" do
 forvin \
 {stretch,jessie}{,/slim} \
  alpine{3.9,3.8} \
- windows/windowsservercore-{ltsc2016,1709,1803,1809} \
+ windows/windowsservercore-{ltsc2016,1803,1809} \
 ;do
  dir="$version/$v"
  variant="$(basename "$v")"

3.6/windows/windowsservercore-1709/Dockerfile

@@ -115,7 +115,7 @@ for version in "${versions[@]}" do
 forvin \
  alpine{3.8,3.9} \
 {jessie,stretch}{/slim,} \
- windows/windowsservercore-{1809,1803,1709,ltsc2016} \
+ windows/windowsservercore-{1809,1803,ltsc2016} \
 ;do
  dir="$version/$v"
  variant="$(basename "$v")"
@@ -187,7 +187,7 @@ for version in "${versions[@]}" do
  travisEnv='\n - os: windows\n dist: 1803-containers\n env: VERSION='"$version VARIANT=$v$travisEnv"
  ;
 
- windows/*-1709 | windows/*-1809) ; # no AppVeyor support for 1709 or 1809 yet: https://github.com/appveyor/ci/issues/1885 and https://github.com/appveyor/ci/issues/2676
+ windows/*-1809) ; # no AppVeyor support for 1809 yet: https://github.com/appveyor/ci/issues/1885 and https://github.com/appveyor/ci/issues/2676
 
  windows/*)
  appveyorEnv='\n - version: '"$version"'\n variant: '"$variant$appveyorEnv"