.github-ci.yml: Pypy is currently Python 3.6, not 3.7

See merge request !160

Currently pymarc complains about different errors depending on how much
is truncated. This exception helps find the root cause.

MarcReader should never raise any exceptions, this greatly simplifies error
handling and eliminates a lot of confusion when incoming data contains
badly formatted records.

This is the alternative approach to !158 

Also, Python is a proper noun so let's capitalize it.

Signed-off-by: Dan Scott <dan@coffeecode.net>

record.py: Format using # fmt: on/off directives

See merge request !165

Truncated record data

See merge request !161

Update version in setup.py and

See merge request !164

Python type hints in leader.py

See merge request !167

Adds type hints for writer module

See merge request !170

Type hints in field.py

See merge request !169

Python type hints in marc8.py

See merge request !172

Make MARCReader always permissible.

See merge request !162

Fixes #163

Fix .gitlab ci.yml

Closes #163

See merge request !174

Type hints enabled for reader module

See merge request !171

Replaces assertEquals with singular

See merge request !173

Fixes #161

Make record.fields a list, not an iterator in map_marc8_record

Closes #161

See merge request !176

.gitlab-ci.yml: Re-enable type checking with mypy

See merge request !175

Add a convenient function for getting subfields as a dictionary

See merge request !178

Since pypy envs are causing testing problems and I've personally not
heard of anyone using pymarc with pypy I'm dropping it for now.

New version which includes the new Field.subfields_as_dict() method.

The Field.subfields_as_dict method now takes a repeatable parameter,
which when set to True, will return a dictionary that maps subfield
codes to a list of subfield values.

Fixes #170

After further consideration its probably best if Field.subfields_as_dict
always returns a mapping of subfield codes and values where the values
are a list (since subfield codes can and do repeat). If the default
behavior ignores this possibility then we are encouraging pymarc users
to ignore the fact that a value they are looking for could be there.

refs #170

Updated docstring and informational URL for sudoc

See merge request !182

Given the move of #code4lib IRC from Freenode to Libera, this updates
the references in the readmes accordingly.

(readme) freenode --> libera

See merge request !183