Fix compatibility with urllib3-future

`grafana-client` uses the `niquests` package, which pulls in
`urllib3-future` instead of vanilla `urllib3`. There was a subtle
incompatibility.

Author: amotl

CHANGES.rst

@@ -12,6 +12,8 @@ Unreleased
 
 - Parse path prefixes from server URLs and propagate them to all requests.
 
+- Fixed compatibility with ``urllib3-future``.
+
 2025/01/30 2.0.0
 ================
 

src/crate/client/http.py

@@ -187,7 +187,7 @@ def request(
         if "Content-Length" not in headers:
             length = super_len(data)
             if length is not None:
-                headers["Content-Length"] = length
+                headers["Content-Length"] = str(length)
 
         # Authentication credentials
         if username is not None:

tests/client/test_http.py

@@ -192,7 +192,12 @@ def test_redirect_handling():
     # - https://github.com/crate/crate-python/issues/179
     # - https://github.com/crate/crate-python/issues/180
 
-    assert client.server_pool["http://localhost:4201"].pool.conn_kw == {
+    # Remove some optional server pool parameters added by `urllib3-future`.
+    conn_kw = client.server_pool["http://localhost:4201"].pool.conn_kw
+    conn_kw.pop("keepalive_delay")
+    conn_kw.pop("resolver")
+
+    assert conn_kw == {
         "socket_options": _get_socket_opts(keepalive=True)
     }