Release 2.1 is Breaking for Jinja2<3.0

[rmorshea]

pip install Jinja2<3.0

Python 3.9.0 (default, Dec  4 2020, 20:11:05) 
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import jinja2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/ryan/Repositories/idom-team/idom/.nox/test_python_suite/lib/python3.9/site-packages/jinja2/__init__.py", line 12, in <module>
    from .environment import Environment
  File "/home/ryan/Repositories/idom-team/idom/.nox/test_python_suite/lib/python3.9/site-packages/jinja2/environment.py", line 25, in <module>
    from .defaults import BLOCK_END_STRING
  File "/home/ryan/Repositories/idom-team/idom/.nox/test_python_suite/lib/python3.9/site-packages/jinja2/defaults.py", line 3, in <module>
    from .filters import FILTERS as DEFAULT_FILTERS  # noqa: F401
  File "/home/ryan/Repositories/idom-team/idom/.nox/test_python_suite/lib/python3.9/site-packages/jinja2/filters.py", line 13, in <module>
    from markupsafe import soft_unicode
ImportError: cannot import name 'soft_unicode' from 'markupsafe' (/home/ryan/Repositories/idom-team/idom/.nox/test_python_suite/lib/python3.9/site-packages/markupsafe/__init__.py)

[rmorshea]

You can just require markupsafe<2.1 to work around this, but I figured I'd report in case this wasn't intentional or in case this is something that should be reported to Jinja instead.

[davidism]

Duplicate of #282

You are using an unsupported version of Jinja, please update to the latest version. Additionally, please read https://hynek.me/articles/semver-will-not-save-you/, then use a tool like pip-tools to pin your dependencies and control when you get updates. Be sure to run your tests with deprecation warnings treated as errors so that you get notified of these types of changes early.