Roll customer_testing from b4cc09721 to 6a6d0963c (3 commits)

Looks like this is the first roll since this pin was introduced
in flutter#162041 / flutter#162048.

For fun and the possible convenience of the next person doing one of
these, here's the command I used to generate the log below:

    $ git log --oneline --no-decorate --format='%cs %aE %s' b4cc09721.. \
        | perl -pe 's,#,flutter/tests#,g'

flutter/tests@b4cc097...6a6d096

2025-02-05 greg@zulip.com Re-land "Update Zulip tests and re-enable (flutter/tests#441)" (flutter/tests#446)
2025-01-30 goderbauer@google.com Update contact for pkg:animations (flutter/tests#447)
2025-01-24 matanlurey@users.noreply.github.com Add a PR template that explains updating `tests.version` (flutter/tests#445)

Author: gnprice

dev/customer_testing/tests.version

@@ -1 +1 @@
-b4cc097211814cfb0e1f08affb4574cf7de6b1cd
+6a6d0963c486da4c0b9387e5a5f6674877023064