jammy-amd64-tf-a-build-lts2.8: Capture Python requirements prior to Sphinx 5

We relied on shared Python requirements with the mainline, but mainline was
recently upgraded to Sphinx 5, causing issues with the lts2.8 branch.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I45368cda3fd067bfaf2915b0c4d268d13504ba2a
2 files changed