Move to Poetry for deps and packaging

setup.py has been removed, and Poetry is now used to package for
install. This fixed an issue i had with uploading to PyPI, so one can
now run 'pip install jellyfin-accounts' to install.

jellyfin_accounts/data/static/site.webmanifest

@@ -0,0 +1,19 @@
+{
+    "name": "jf-accounts",
+    "short_name": "jf-accounts",
+    "icons": [
+        {
+            "src": "/android-chrome-192x192.png",
+            "sizes": "192x192",
+            "type": "image/png"
+        },
+        {
+            "src": "/android-chrome-512x512.png",
+            "sizes": "512x512",
+            "type": "image/png"
+        }
+    ],
+    "theme_color": "#ffffff",
+    "background_color": "#ffffff",
+    "display": "standalone"
+}