fastentrypoints enforces dependencies

[bertsky]

In #882 we introduced fastentrypoints, replacing pkg_resources so our processors would spin up faster.

However, it seems that this causes the entry point to put a hard constraint on all package requirements, e.g. when using Torch 2.0.1 despite Kraken allowing only <1.14 (for no good reason BTW):

crash log

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 629, in _build_master
    ws.require(__requires__)
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 966, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 827, in resolve
    dist = self._resolve_dist(
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 873, in _resolve_dist
    raise VersionConflict(dist, req).with_context(dependent_req)
pkg_resources.ContextualVersionConflict: (torch 2.0.1+cu118 (/usr/local/lib/python3.8/site-packages), Requirement.parse('torch<1.14,>=1.11'), {'kraken'})

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/bin/ocrd-kraken-segment", line 33, in <module>
    sys.exit(load_entry_point('ocrd-kraken', 'console_scripts', 'ocrd-kraken-segment')())
  File "/usr/local/bin/ocrd-kraken-segment", line 25, in importlib_load_entry_point
    return next(matches).load()
  File "/usr/lib/python3.8/importlib/metadata.py", line 77, in load
    module = import_module(match.group('module'))
  File "/usr/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 848, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/build/ocrd_kraken/ocrd_kraken/cli/segment.py", line 2, in <module>
    from ocrd.decorators import ocrd_cli_options, ocrd_cli_wrap_processor
  File "/build/core/ocrd/ocrd/__init__.py", line 17, in <module>
    from ocrd.processor.base import run_processor, run_cli, Processor
  File "/build/core/ocrd/ocrd/processor/__init__.py", line 1, in <module>
    from .base import (
  File "/build/core/ocrd/ocrd/processor/base.py", line 12, in <module>
    from pkg_resources import resource_filename
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3327, in <module>
    def _initialize_master_working_set():
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3301, in _call_aside
    f(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3339, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 631, in _build_master
    return cls._build_from_requirements(__requires__)
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 644, in _build_from_requirements
    dists = ws.resolve(reqs, Environment())
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 827, in resolve
    dist = self._resolve_dist(
  File "/usr/local/lib/python3.8/site-packages/pkg_resources/__init__.py", line 868, in _resolve_dist
    raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'torch<1.14,>=1.11' distribution was not found and is required by kraken

This goes away when replacing the entry point by the simple direct importer again.

[bertsky]

Reverted via #1041