Fix get_resource_path to work with python eggs, move appdata xml file to src so flatpak can see it, reduce python dependencies, and update release docs

desktop/pyproject.toml

@@ -14,19 +14,9 @@ icon = "src/onionshare/resources/onionshare"
 sources = ['src/onionshare']
 requires = [
     "./onionshare_cli-2.3.dev1-py3-none-any.whl",
-    "Click",
-    "eventlet",
-    "Flask",
-    "Flask-HTTPAuth",
-    "flask-socketio",
     "psutil",
-    "pycryptodome",
-    "PySocks",
     "pyside2==5.15.1",
-    "qrcode",
-    "requests",
-    "stem",
-    "urllib3",
+    "qrcode"
 ]
 
 [tool.briefcase.app.onionshare.macOS]

desktop/src/onionshare/gui_common.py

@@ -21,6 +21,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 import os
 import inspect
 import shutil
+from pkg_resources import resource_filename
 
 from . import strings
 from onionshare_cli.onion import Onion
@@ -367,8 +368,4 @@ class GuiCommon:
         """
         Returns the absolute path of a resource
         """
-        resources_path = os.path.join(
-            os.path.dirname(os.path.abspath(inspect.getfile(inspect.currentframe()))),
-            "resources",
-        )
-        return os.path.join(resources_path, filename)
+        return resource_filename("onionshare", os.path.join("resources", filename))