Bug 1916970 - add min TLS version to mitmproxy command TLS1_2 r=perftest-reviewers,sparky

Differential Revision: https://phabricator.services.mozilla.com/D221456

testing/mozbase/mozproxy/mozproxy/backends/mitm/mitm.py

@@ -307,6 +307,8 @@ class Mitmproxy(Playback):
                             "--set",
                             "alt_server_replay_order_reversed=true",
                             "--set",
+                            "tls_version_client_min=TLS1_2",
+                            "--set",
                             "alt_server_replay={}".format(
                                 ",".join(
                                     [