validate-krew-manifest: Add windows/arm64 to supported platforms (#747)

Author: superbrothers

cmd/validate-krew-manifest/main.go

@@ -237,6 +237,7 @@ func allPlatforms() []installation.OSArchPair {
 	return []installation.OSArchPair{
 		{OS: "windows", Arch: "386"},
 		{OS: "windows", Arch: "amd64"},
+		{OS: "windows", Arch: "arm64"},
 		{OS: "linux", Arch: "386"},
 		{OS: "linux", Arch: "amd64"},
 		{OS: "linux", Arch: "arm"},