Ignore deprecation warning that comes from external packages

[javierggt]

Description

While preparing ska3-next (sot/skare3/pull/755) some warnings popped up. I added them here to discuss whether to ignore them or fix them before ska3-next. This change causes the warnings to be ignored.

• Since Numpy 1.20.0, numpy.object is deprecated. PyTable still uses it and this shows this warning:

  `np.object` is a deprecated alias for the builtin `object`
  

• conda-build requires jinja2 <3.0.0, and jinja2 2.* together with MarksupSafe lead to this warning:

  'soft_unicode' has been renamed to 'soft_str'
  

• a warning in annie I have not yet decided what to do with.

Testing

• [n/a] Passes unit tests on MacOS, linux, Windows (at least one required)
• Functional testing: all run_testr tests pass if the proseco, acis_thermal_check, starcheck and Ska.Matplotlib PRs are merged.

Fixes #

[javierggt]

This is one of the issues for ska3-next