Need support for the latest version of Starlette

[russian-developer]

I've found that the latest release of gino-stralette (0.1.1) doesn't support the latest version of Starlette (0.14.2).
It requires >0.14.0.

[frall88]

I faced with the issue in my fastapi app when trying to update fastapi version due to security issue:

 Because no versions of fastapi match >0.65.1,<0.66.0
   and fastapi (0.65.1) depends on starlette (0.14.2), fastapi (>=0.65.1,<0.66.0) requires starlette (0.14.2).
  Because gino-starlette (0.1.1) depends on starlette (>=0.13.0,<0.14.0)
   and no versions of gino-starlette match >0.1.1,<0.2.0, gino-starlette (>=0.1.1,<0.2.0) requires starlette (>=0.13.0,<0.14.0).
  Thus, fastapi (>=0.65.1,<0.66.0) is incompatible with gino-starlette (>=0.1.1,<0.2.0).
  And because gino[pg,starlette] (1.0.1) depends on gino-starlette (>=0.1.1,<0.2.0)
   and no versions of gino match >1.0.1,<2.0.0, fastapi (>=0.65.1,<0.66.0) is incompatible with gino[pg,starlette] (>=1.0.1,<2.0.0).
  So, because marketplace depends on both fastapi (^0.65.1) and gino[pg,starlette] (^1.0.1), version solving failed.

[wwwjfy]

fixed via #24