make UnparsedVersion.__lt__ order-agnostic

[MichelleArk]

resolves #8571
docs dbt-labs/docs.getdbt.com/#

Problem

The current implementation of UnparsedVersion.__lt__ is sensitive to the order of arguments, leading to surprising behaviour such as:

>>> from dbt.contracts.graph.unparsed import UnparsedVersion
>>> UnparsedVersion(12) < UnparsedVersion("2")
True
>>> UnparsedVersion(12) > UnparsedVersion("2")
True

The root cause is that UnparsedVersion.lt first attempts to cast self.v to other's type in order to do the comparison, and if that fails then attempts to cast other.v to self type. This means that casting may work in some directions but not others and result in different comparison methods (e.g. numeric vs alphabetic) depending on which input is self and which is other.

Solution

UnparsedVersion.v is either float or str. Simplify the lt implementation to just try to cast both inputs to floats and do a numeric comparison, falling back to str if this is not posssible -- making the method insensitive to order but more tightly coupled to the type of UnparsedVersion.v

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX

[github-actions]

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[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (a0e1356) 86.37% compared to head (4c20c35) 86.37%.
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #8559   +/-   ##
=======================================
  Coverage   86.37%   86.37%           
=======================================
  Files         174      174           
  Lines       25587    25582    -5     
=======================================
- Hits        22100    22096    -4     
+ Misses       3487     3486    -1     

Flag	Coverage Δ
integration	83.17% <100.00%> (+<0.01%)	⬆️
unit	65.06% <100.00%> (+0.01%)	⬆️

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Files Changed	Coverage Δ
core/dbt/contracts/graph/unparsed.py	93.43% <100.00%> (+0.31%)	⬆️

... and 2 files with indirect coverage changes

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