Add Python requirements from framework/util

Any `all.sh` component that runs a script that requires a more recent
version of Python must have a `support_xxx` function that checks for the
requisite Python version or package. At this time, there is no such
requirement yet in the mbedtls repository.

The directory `framework/util` is not yet checked by `pylint` or `mypy`,
because we use older versions of these tools that don't work well with
modern Python versions.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

scripts/ci.requirements.txt

@@ -17,3 +17,9 @@ pylint == 2.4.4; platform_system == 'Linux'
 #   https://github.com/Mbed-TLS/mbedtls-framework/issues/50
 # mypy 0.942 is the version in Ubuntu 22.04.
 mypy == 0.942; platform_system == 'Linux'
+
+# More requirements for scripts in the framework that might not work in
+# older versions of Python. Note that requirements that are not available
+# in the oldest version of Python on our CI must be annodated with
+# "python >= ...".
+-r ../framework/util/requirements.txt