Fix some problems in httpie.d.ts

[ghost]

I found some problems in the .d.ts file when trying to use httpie with TypeScript, so I fixed them:

• opts now has type Partial<HttpieOptions> since you don't have to give all 3 options.
• The T in send<T>() and method<T>() now has default type any instead of the implicit {}

[codecov-io]

Codecov Report

Merging #8 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master     #8   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           1      1           
  Lines          40     40           
=====================================
  Hits           40     40

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[lukeed]

Awesome, thank you! As a non-TypeScripter, this actually makes sense to me :D Also didn't know Partial was a thing ... good to know 👍

[ghost]

Thanks. I can use httpie in my projects now!