Fetch Catch from our own clone, instead of the github one.

Avoids:

- Relying on github’s services
- Fetching a new (malicious) version, automatically, without any “check”

CMakeLists.txt

@@ -179,7 +179,7 @@ endif()
 
 include(ExternalProject)
 ExternalProject_Add(catch
-  GIT_REPOSITORY "https://github.com/philsquared/Catch.git"
+  GIT_REPOSITORY "https://lab.louiz.org/louiz/Catch.git"
   PREFIX "external"
   UPDATE_COMMAND ""
   CONFIGURE_COMMAND ""