investigate pinning / build strings

[ltalirz]

Solution to issue cannot be found in the documentation.

• I checked the documentation.

Issue

For some reason, for a given release (e.g. 2.2.2), the build string of the aiida-core package differs from the build string of the dependent packages (aiida-core.services, aiida-core.rest, ...).

When using pin_subpackage with exact=True, this prevents the installation of aiida-core into the same conda environment as other subpackages

#85 will therefore switch to pinning with exact=False, but we should investigate whether pinning can be made stricter again in the future.

See #76 (comment) for additional context

[ltalirz]

addressed by #85