fix: Pin TDS version back to 7.0

pymssql with TDS 7.3 parses datetime2 as datetime, leading
to a drop in timestamp resolution (100 ns -> ~3 ms). This causes
incorrect frames to occasionally be grabbed from Beholder.

vars_gridview/lib/sql.py

@@ -91,7 +91,7 @@ def connect(server_url: str, user: str, password: str, database: str):
         user=user,
         password=password,
         database=database,
-        tds_version="7.3",
+        tds_version="7.0",
     )