implement spell-checking in Dockerfile.test

[modernNeo]

https://github.com/pylint-dev/pylint https://pylint.readthedocs.io/en/latest/user_guide/configuration/all-options.html#spelling-checker https://pyenchant.github.io/pyenchant/install.html

currently blocked by:

To detect the libenchant binaries, PyEnchant uses [ctypes.util.find_library()]  
(https://docs.python.org/3/library/ctypes.html#finding-shared-libraries), which requires ldconfig, gcc, objdump or ld to be installed.  
This is the case on most major distributions, however statically  
linked distributions (like Alpine Linux) might not bring along binutils by default.

• https://github.com/pyenchant/pyenchant/issues/164
• https://github.com/docker-library/python/issues/111
• https://github.com/python/cpython/issues/65821
• https://github.com/python/cpython/pull/18380