Update MIRI MRS TSO regtest

[hbushouse]

Related to JP-3359

This PR updates the MIRI MRS TSO regression test to temporarily skip the MRS time-dependent correction in the photom step of the spec2 pipeline, because that algorithm can't handle 3D MRS data right now. Previously, the test had been working OK, because the DATE-OBS in the input file was pre-flight, such that an old photom ref file was used, which did not contain the time-dependent corrections, so no error occurred. This, however, allowed that error to get through our B9.3 testing and into operations. So I've updated the DATE-OBS in the test input file to use the most recent ref files, which will trigger the error, until it gets fixed by JP-3359.

Checklist for maintainers

• added entry in CHANGES.rst within the relevant release section
• updated or added relevant tests
• updated relevant documentation
• added relevant milestone
• added relevant label(s)
• ran regression tests, post a link to the Jenkins job below.
  How to run regression tests on a PR
• Make sure the JIRA ticket is resolved properly

[tapastro]

Should we have a set of regtests than can be run with a datetime override, such that the obstime is set to the current time? I assume this won't work for all tests, but it seems like it might be useful for test coverage of CRDS updates.