Update Jinja2 to fix pallets/jinja#1585

Author: judahrand

setup.cfg

@@ -77,7 +77,7 @@ install_requires =
     # importlib_metadata backport for python 3.7
     # Require versions with .distributions https://github.com/sqlfluff/sqlfluff/issues/3763
     importlib_metadata>=1.0.0; python_version < '3.8'
-    Jinja2
+    Jinja2>=3.1.2
     # Used for .sqlfluffignore
     pathspec
     # We provide a testing library for plugins in sqlfluff.utils.testing