fix(ko): error finishing with .

internal/pipe/ko/ko.go

@@ -50,7 +50,7 @@ var (
 	)
 
 	errNoRepository    = errors.New("ko: missing repository: please set either the repository field or a $KO_DOCKER_REPO environment variable")
-	errInvalidMainPath = errors.New("ko: invalid Main path: ko.main (or build.main if ko.main is not set) should be a relative path.")
+	errInvalidMainPath = errors.New("ko: invalid Main path: ko.main (or build.main if ko.main is not set) should be a relative path")
 )
 
 // Pipe that build OCI compliant images with ko.