do not escape {} in URL(*parts)

Author: mdipierro

py4web/core.py

@@ -897,7 +897,7 @@ def URL(  # pylint: disable=invalid-name
             broken_parts.insert(1, "_" + static_version)
 
     url_prefix = os.environ.get("PY4WEB_URL_PREFIX", "")
-    url = url_prefix + prefix + "/".join(map(urllib.parse.quote, broken_parts))
+    url = url_prefix + prefix + "/".join(urllib.parse.quote(part, safe=r":/{}") for part in broken_parts)
     # Signs the URL if required.  Copy vars into urlvars not to modify it.
     urlvars = dict(vars) if vars else {}
     if signer:
@@ -906,7 +906,7 @@ def URL(  # pylint: disable=invalid-name
         signer.sign(prefix + "/".join(broken_parts), urlvars)
     if urlvars:
         url += "?" + "&".join(
-            f"{k}={urllib.parse.quote(str(v))}"
+            f"{k}=" + urllib.parse.quote(str(v), safe=r":/{}")
             for k, v in urlvars.items()
             if v is not None
         )