proxy: update tokio-postgres to allow arbitrary config params (#8076)

## Problem

Fixes https://github.com/neondatabase/neon/issues/1287

## Summary of changes

tokio-postgres now supports arbitrary server params through the
`param(key, value)` method. Some keys are special so we explicitly
filter them out.

test_runner/regress/test_proxy.py

@@ -53,6 +53,25 @@ def test_proxy_select_1(static_proxy: NeonProxy):
     assert out[0][0] == 42
 
 
+def test_proxy_server_params(static_proxy: NeonProxy):
+    """
+    Test that server params are passing through to postgres
+    """
+
+    out = static_proxy.safe_psql(
+        "select to_json('0 seconds'::interval)", options="-c intervalstyle=iso_8601"
+    )
+    assert out[0][0] == "PT0S"
+    out = static_proxy.safe_psql(
+        "select to_json('0 seconds'::interval)", options="-c intervalstyle=sql_standard"
+    )
+    assert out[0][0] == "0"
+    out = static_proxy.safe_psql(
+        "select to_json('0 seconds'::interval)", options="-c intervalstyle=postgres"
+    )
+    assert out[0][0] == "00:00:00"
+
+
 def test_password_hack(static_proxy: NeonProxy):
     """
     Check the PasswordHack auth flow: an alternative to SCRAM auth for