fix latin-1 errors

app/main.py

@@ -11,14 +11,28 @@ app.include_router(router)
 
 
 async def add_geo_headers(request, call_next):
+    import unicodedata
+    from starlette.responses import Response  # tylko dla typu
+
+    def _ascii(s: str) -> str:
+        try:
+            s.encode("latin-1")
+            return s
+        except UnicodeEncodeError:
+            return unicodedata.normalize("NFKD", s).encode("ascii", "ignore").decode("ascii") or "?"
+
     ip = get_client_ip(request)
     geo = get_geo()
     data = geo.lookup(ip)
 
     response: Response = await call_next(request)
 
-    for k, v in geo_headers(data).items():
-        response.headers[k] = v
+    for k, v in (geo_headers(data) or {}).items():
+        ks = _ascii(str(k))
+        vs = _ascii(str(v))
+        # gwarancja, że przejdzie przez kodowanie nagłówków Starlette
+        response.headers[ks] = vs
+
     return response