replace submodule signs_lib with newer gitlab version

.gitmodules

@@ -131,9 +131,6 @@
 [submodule "mods/sprint"]
 	path = mods/sprint
 	url = https://git.tchncs.de/Illuna-Minetest/sprint
-[submodule "mods/signs_lib"]
-	path = mods/signs_lib
-	url = https://github.com/minetest-mods/signs_lib
 [submodule "mods/replacer"]
 	path = mods/replacer
 	url = https://github.com/Sokomine/replacer
@@ -269,3 +266,6 @@
 [submodule "mods/cloaking"]
 	path = mods/cloaking
 	url = https://github.com/luk3yx/minetest-cloaking
+[submodule "mods/signs_lib"]
+	path = mods/signs_lib
+	url = https://gitlab.com/VanessaE/signs_lib