Merge pull request #19 from DMwangnima/feat/specify_request

feat: support specifying the request to be used each time the SSE stream is created

feat: customize stream writer (#18)

* feat: customize stream writer

* feat: customize stream writer

* feat: customize stream writer

* feat: customize stream writer

* feat: customize stream writer

* feat: customize stream writer

* feat: customize stream writer

* feat: customize stream writer

fix: fix client 'retry' tag (#16)

* fix: fix client 'retry' tag

* feat: optimize client_test

feat: add unsubscribe (#15)

* feat: add unsubscribe

* fix: fix unit_test

* chore: optimize license header

* chore: optimize license header

Feature/add req param (#12)

* feat: add req param

* feat: add get & set

* feat: add set formdata

* style: improve comment

* style: remove space

* chore: remove redundant func

* test:optimize POST body test

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Co-authored-by: violapioggia <2604296771@qq.com>

chore:unify option (#11)

* chore:unify option

* docs:fix a description

* docs:replace validator with callback

* chore:change client struct

fix: use ChunkedBodyWriter (#2)