Fastapi-code-generator

- update datamodel-code-generator to 0.6.17 [83]
- Support multi-line string values for openapi keys [80] by bpow

Thanks to bpow

- move black to dev dependencies [65]

- support summary [63]

- Support python39 [59]
- Support python37 [58]
- Support remote ref on parameters, requestBodies and responses [57]
- Use re.compiled object [50] by ioggstream

Thanks to ioggstream

- support $ref paramter [49]

- support application json variant [47 ]