Add tests for different Postgres client libraries (#2008)

* Add tests for different postgres clients
* test/fixtures: sanitize test name for test_output_dir
* test/fixtures: do not look for etcd before runtime
* Add workflow for testing Postgres client libraries

test_runner/pg_clients/python/pg8000/pg8000_example.py

@@ -0,0 +1,23 @@
+#! /usr/bin/env python3
+
+import os
+import ssl
+
+import pg8000.dbapi
+
+if __name__ == "__main__":
+    kwargs = {
+        k.lstrip("NEON_").lower(): v
+        for k in ("NEON_HOST", "NEON_DATABASE", "NEON_USER", "NEON_PASSWORD")
+        if (v := os.environ.get(k, None)) is not None
+    }
+    conn = pg8000.dbapi.connect(
+        **kwargs,
+        ssl_context=True,
+    )
+
+    cursor = conn.cursor()
+    cursor.execute("SELECT 1")
+    row = cursor.fetchone()
+    print(row[0])
+    conn.close()