doctor: Fix regular expression identified by CodeQL

CodeQL identified "This regular expression has an unescaped dot before
'com', so it might match more hosts than expected when used ."

Signed-off-by: Tom Payne <tom@isovalent.com>

tools/dev-doctor/rootcmd.go

@@ -81,7 +81,7 @@ func rootCmdRun(cmd *cobra.Command, args []string) {
 			command:       "docker",
 			ifNotFound:    checkWarning,
 			versionArgs:   []string{"buildx", "version"},
-			versionRegexp: regexp.MustCompile(`github.com/docker/buildx v(\d+\.\d+\.\d+)`),
+			versionRegexp: regexp.MustCompile(`github\.com/docker/buildx v(\d+\.\d+\.\d+)`),
 			hint:          "see https://docs.docker.com/engine/install/",
 		},
 		// FIXME add libelf-devel check?