external open-source: Move to https repo

Author: bramoosterhuis

.gitmodules

@@ -3,7 +3,7 @@
 	url = https://github.com/buildroot/buildroot.git
 [submodule "buildroot-external-metrological-open-source"]
 	path = buildroot-external-metrological-open-source
-	url = git@github.com:Metrological/buildroot-external-metrological-open-source.git
+	url = https://github.com/Metrological/buildroot-external-metrological-open-source.git
 [submodule "buildroot-external-metrological-restricted"]
 	path = buildroot-external-metrological-restricted
 	url = [email protected]:Metrological/buildroot-external-metrological-restricted.git