fix: poetry analyzer crashed with certain optional package's version constraints

[jkowalleck]

fixes #702

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ -0.06% (target: -1.00%)	✅ 92.31% (target: 80.00%)

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (59f07c1)	1023	988	96.58%
Head commit (0cb8750)	1034 (+11)	998 (+10)	96.52% (-0.06%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#703)	13	12	92.31%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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