* Updated relay/channel/gemini package to use gin-gonic/gin for routing
* Added timeouts, environment variable for proxy, and error handling for HTTP clients in relay/util/init.go
* Improved error handling, URL path cases, and channel selection logic in middleware/distributor.go
* Added Content-Type header, closed request bodies, and added context to requests in relay/channel/common.go
* Upgraded various dependencies in go.mod
* Modified the GetRequestURL method in relay/channel/gemini/adaptor.go to include a "key" parameter in the URL and set a default version of "v1beta"
* Added io and net/http packages in relay/channel/gemini/adaptor.go and relay/channel/gemini/main.go
* Added a struct for GeminiStreamResp and modified response handling in relay/channel/gemini/main.go
* Imported packages for io and net/http added, gin-gonic/gin package added, and error handling improved in relay/channel/gemini/main.go
- Introduced idle connection timeout for HTTP client transport
- Implemented custom timeout for HTTP client when `RelayTimeout` is 0
- Set ImpatientHTTPClient timeout to 5 seconds
- Added new config variable `IdleTimeout` with default value of 30 seconds
- Utilized shared transport object for all HTTP clients in relay/util package
