Remove EOL Windows 1803-based (SAC) images

See https://docs.microsoft.com/en-us/virtualization/windowscontainers/deploy-containers/base-image-lifecycle (EOL 11/12/2019)

Author: tianon

.travis.yml

@@ -3,18 +3,12 @@ services: docker
 
 matrix:
   include:
-    - os: windows
-      dist: 1803-containers
-      env: VERSION=3.8 VARIANT=windows/windowsservercore-1803
     - os: linux
       env: VERSION=3.8 VARIANT=buster
     - os: linux
       env: VERSION=3.8 VARIANT=buster/slim
     - os: linux
       env: VERSION=3.8 VARIANT=alpine3.10
-    - os: windows
-      dist: 1803-containers
-      env: VERSION=3.7 VARIANT=windows/windowsservercore-1803
     - os: linux
       env: VERSION=3.7 VARIANT=buster
     - os: linux
@@ -51,9 +45,6 @@ matrix:
       env: VERSION=3.5 VARIANT=alpine3.10
     - os: linux
       env: VERSION=3.5 VARIANT=alpine3.9
-    - os: windows
-      dist: 1803-containers
-      env: VERSION=2.7 VARIANT=windows/windowsservercore-1803
     - os: linux
       env: VERSION=2.7 VARIANT=buster
     - os: linux

2.7/windows/windowsservercore-1803/Dockerfile

@@ -81,7 +81,7 @@ for version in "${versions[@]}"; do
 	for v in \
 		{buster,stretch}{,/slim} \
 		alpine{3.10,3.9} \
-		windows/windowsservercore-{ltsc2016,1803,1809} \
+		windows/windowsservercore-{ltsc2016,1809} \
 	; do
 		dir="$version/$v"
 		variant="$(basename "$v")"

3.7/windows/windowsservercore-1803/Dockerfile

@@ -118,7 +118,7 @@ for version in "${versions[@]}"; do
 	for v in \
 		alpine{3.9,3.10} \
 		{stretch,buster}{/slim,} \
-		windows/windowsservercore-{1809,1803,ltsc2016} \
+		windows/windowsservercore-{1809,ltsc2016} \
 	; do
 		dir="$version/$v"
 		variant="$(basename "$v")"
@@ -187,10 +187,6 @@ for version in "${versions[@]}"; do
 		fi
 
 		case "$v" in
-			windows/*-1803)
-				travisEnv='\n    - os: windows\n      dist: 1803-containers\n      env: VERSION='"$version VARIANT=$v$travisEnv"
-				;;
-
 			windows/*-1809) ;; # no AppVeyor support for 1809 yet: https://github.com/appveyor/ci/issues/1885 and https://github.com/appveyor/ci/issues/2676
 
 			windows/*)