feat(REST): change api version to v9

[vaporoxx]

Please describe the changes this PR makes and why it should be merged:

This updates the API version to v9. The change log doesn't mention any relevant changes, so I think this should be it

Status and versioning classification:

• Typings don't need updating

[codecov]

Codecov Report

Merging #62 (b6b535b) into main (c4b2803) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main      #62   +/-   ##
=======================================
  Coverage   85.80%   85.80%           
=======================================
  Files           8        8           
  Lines        1000     1000           
  Branches      100      100           
=======================================
  Hits          858      858           
  Misses         42       42           
  Partials      100      100           

Impacted Files	Coverage Δ
packages/rest/src/lib/REST.ts	95.45% <100.00%> (ø)
packages/rest/src/lib/utils/constants.ts	100.00% <100.00%> (ø)

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[vladfrangu]

Is our code already in v9? If so, LGTM.