fix: copy submodules when building the snap (#206)

README

@@ -58,6 +58,12 @@ Landscape service. There are two ways to do this:
 
 ## Developing
 
+After cloning the repository, make sure you run the following command to pull the `snap-http` submodule:
+
+```shell
+git submodule update --init
+```
+
 To run the full test suite, run the following command:
 
 ```

snap/snapcraft.yaml

@@ -86,7 +86,8 @@ parts:
 
        -- Guy Incognito <[email protected]>  Fri, 1 Sep 2023 00:00:00 +0000
       EOF
-      git archive --prefix landscape-client-0.0.1/ HEAD | tar -x
+      mkdir -p landscape-client-0.0.1
+      git ls-files --recurse-submodules | xargs -I {} cp -r --parents {} landscape-client-0.0.1/
       rm -rf landscape-client-0.0.1/debian
       tar -czf landscape-client-0.0.1.tar.gz landscape-client-0.0.1
       cp -r debian landscape-client-0.0.1