Add a tool to check the API against the OpenAPI specification

[mpejcoch]

Make it part of the CI. If the OpenAPI specification doesn't correspond to the API it should not pass the CI.

[ways]

When the service is running, this can be tested like this:

/home/larsfp/src/go-mms
> uvx schemathesis run openapi3.yaml --url http://localhost:8080 
Schemathesis v4.12.0
━━━━━━━━━━━━━━━━━━━━

 ✅  Loaded specification from openapi3.yaml (in 0.51s)                                                                                         

     Base URL:         http://localhost:8080                                                                                                    
     Specification:    Open API 3.0.2                                                                                                           
     Operations:       3 selected / 3 total                                                                                                     

 ✅  API capabilities:                                                                                                                          

     Supports NULL byte in headers:    ✘                                                                                                        

 ⏭   Examples (in 0.12s)                                                                                                                        
                                                                                                                                                
     ⏭  3 skipped                                                                                                                               

 ❌  Coverage (in 0.15s)                                                                                                                        
                                                                                                                                                
     ❌ 3 failed                                                                                                                                

 ❌  Fuzzing (in 0.25s)                                                                                                                         
                                                                                                                                                
     ✅ 2 passed  ❌ 1 failed                                                                                                                   

=================================================================== FAILURES ===================================================================
_____________________________________________________________ TRACE /api/v1/about ______________________________________________________________
1. Test Case ID: rS7iwc

- Unsupported methods
...