remove windows 20H2 build since it's EOL long time ago

remove windows 20H2 build since it's EOL more than one year ago

prow.sh

@@ -78,7 +78,7 @@ version_to_git () {
 # the list of windows versions was matched from:
 # - https://hub.docker.com/_/microsoft-windows-nanoserver
 # - https://hub.docker.com/_/microsoft-windows-servercore
-configvar CSI_PROW_BUILD_PLATFORMS "linux amd64 amd64; linux ppc64le ppc64le -ppc64le; linux s390x s390x -s390x; linux arm arm -arm; linux arm64 arm64 -arm64; linux arm arm/v7 -armv7; windows amd64 amd64 .exe nanoserver:1809 servercore:ltsc2019; windows amd64 amd64 .exe nanoserver:20H2 servercore:20H2; windows amd64 amd64 .exe nanoserver:ltsc2022 servercore:ltsc2022" "Go target platforms (= GOOS + GOARCH) and file suffix of the resulting binaries"
+configvar CSI_PROW_BUILD_PLATFORMS "linux amd64 amd64; linux ppc64le ppc64le -ppc64le; linux s390x s390x -s390x; linux arm arm -arm; linux arm64 arm64 -arm64; linux arm arm/v7 -armv7; windows amd64 amd64 .exe nanoserver:1809 servercore:ltsc2019; windows amd64 amd64 .exe nanoserver:ltsc2022 servercore:ltsc2022" "Go target platforms (= GOOS + GOARCH) and file suffix of the resulting binaries"
 
 # If we have a vendor directory, then use it. We must be careful to only
 # use this for "make" invocations inside the project's repo itself because