Use native fetch, remove tmp dependency

[blampe]

Node 18 introduced native fetch. Pulumi already requires at least 18, so we can use this instead of node-fetch to resolve the punycode deprecation warning.

Also remove the tmp dependency which was only used in Helm v2 and removed in #2396.

Fixes #3301.

[github-actions]

Does the PR have any schema changes?

Looking good! No breaking changes found.
No new resources/functions.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 41.08%. Comparing base (27bc9a1) to head (87f511b).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
provider/pkg/gen/schema.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3308      +/-   ##
==========================================
+ Coverage   41.06%   41.08%   +0.01%     
==========================================
  Files          85       85              
  Lines       12740    12736       -4     
==========================================
  Hits         5232     5232              
+ Misses       7119     7115       -4     
  Partials      389      389              

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