chore: Updates version specifiers & conda recipe

[frgfm]

This PR introduces the following modifications:

• adds upper bound for deps to avoid conflicts with upcoming releases
• fixes conda recipe (not compatible with the pyproject.toml definition from #138)

Any feedback is welcome!

[codecov[bot]]

Codecov Report

Merging #145 (6d90a84) into master (eee9e54) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #145   +/-   ##
=======================================
  Coverage   89.16%   89.16%           
=======================================
  Files           8        8           
  Lines         203      203           
=======================================
  Hits          181      181           
  Misses         22       22           

Flag	Coverage Δ
unittests	89.16% <ø> (ø)

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