Require an older version of markupsafe for the sake of older Jinja2
Require an older version of markupsafe for the sake of older Jinja2

Jinja2 <3.0 require markupsafe <2.1.0, but does not declare this
requirement. (Jinja2 2.x has not been updated since markupsafe 2.1.0 came
out). So declare this requirement ourselves.

This is not ideal, since we would want to use the latest markupsafe with the
latest Jinja2. But at least it gives us a consistent set of versions to run
the CI with.

Signed-off-by: Gilles Peskine <f805f64266d288fc5467baa7be6cd0ff366f477b@arm.com>

ARMmbed/mbedtls,NXPmicro/mbedtls,Mbed-TLS/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,Mbed-TLS/mbedtls,NXPmicro/mbedtls,NXPmicro/mbedtls,NXPmicro/mbedtls,ARMmbed/mbedtls