Enable use of enviornmental variable version pin dictionary

[nanglo123]

This draft PR enables users to define a prefix to version mapping stored in an environmental variable: VERSION_PINS which will allow users to define the configured version they would like to use for a resource to avoid downloading new versions of the resource. The problem with the current argument-based approach is that in many settings PyOBO is being accessed indirectly so it would be very inconvenient to control versions via function arguments.

Places in the code where bioversions.get_versions is used has been replaced by pyobo.api.utils.get_version as we call bioversions.get_versions in pyobo.api.utils.get_version. Please let me know if this change is not needed.

[bgyori]

The linter complains about the following:

mypy: commands[0]> mypy --install-types --non-interactive --ignore-missing-imports src/pyobo/
src/pyobo/sources/biogrid.py:68: error: Argument "version" to "prefix_directory_join" has incompatible type "partial[str | None]"; expected "str | Callable[[], str] | None"  [arg-type]
Found 5 errors in 4 files (checked 149 source files)
src/pyobo/sources/mesh.py:336: error: Argument "version" to "get_tree_to_mesh_id" has incompatible type "str | None"; expected "str"  [arg-type]
src/pyobo/xrefdb/sources/pubchem.py:26: error: Argument "version" to "get_pubchem_id_to_mesh_id" has incompatible type "str | None"; expected "str"  [arg-type]
src/pyobo/cli/lookup.py:285: error: Too many positional arguments for "get_name_by_curie"  [misc]
src/pyobo/cli/lookup.py:298: error: Too many positional arguments for "get_name_by_curie"  [misc]