fix(gen): disallow non-numeric enum with format

[tdakkota]

No description provided.

[codecov]

Codecov Report

Merging #331 (58b111a) into main (41863c9) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #331      +/-   ##
==========================================
- Coverage   67.97%   67.95%   -0.03%     
==========================================
  Files         119      119              
  Lines        8023     8026       +3     
==========================================
  Hits         5454     5454              
- Misses       2228     2230       +2     
- Partials      341      342       +1     

Impacted Files	Coverage Δ
gen/schema_gen_primitive.go	89.39% <100.00%> (+0.24%)	⬆️
openapi/parser/parse_components.go	91.89% <0.00%> (-8.11%)	⬇️
jsonschema/parser.go	80.12% <0.00%> (-1.90%)	⬇️
gen/schema_gen.go	81.73% <0.00%> (+1.44%)	⬆️
gen/reduce.go	74.28% <0.00%> (+8.57%)	⬆️

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