Project: Use requirements file to install AppImage deps

Switch from using `pipenv sync --system` to using the requirements file
generated from `pipenv requirements`.

The `pipenv sync --system` command (added in #1993)  does not work in
newer versions of pipenv. It uses the python version of the system
rather than the one specified by the --python flag.

The `pipenv requirements` command has been added that only pulls from
the Pipfile.lock file (pypa/pipenv#4959, pypa/pipenv#5200), and fixed
to only dump out requirements for the appropriate system
(see pypa/pipenv#5092).

build_scripts/appimage/appimage.sh

@@ -78,12 +78,14 @@ install_monkey_island_python_dependencies() {
   log_message "Installing island requirements"
 
   log_message "Installing pipenv"
-  "$APPDIR"/AppRun -m pip install pipenv==2022.8.14 || handle_error
+  "$APPDIR"/AppRun -m pip install pipenv || handle_error
   export CI=1
 
   log_message "Installing dependencies"
   pushd "$BUILD_DIR/monkey_island" || handle_error
-  "$APPDIR"/AppRun -m pipenv --python "$APPDIR/AppRun" sync --system || handle_error
+  "$APPDIR"/AppRun -m pipenv --python "$APPDIR/AppRun" requirements > requirements.txt || handle_error
+  "$APPDIR"/AppRun -m pip install -r requirements.txt || handle_error
+  rm requirements.txt
   popd || handle_error
 
   log_message "Uninstalling pipenv (build dependency only)"