enable paralleltest lint check in `pkg/postage`

[vladopajic]

Currently pkg/postage has disabled paralleltest lint check (see golangci.yaml file). This check should be enabled for this package and tests should be corrected to use t.Parallel().

Acceptance criteria:

• enable paralleltest lint check in pkg/postage
  • all tests should use t.Parallel(); if tests for some reason could not use t.Parallel() then it disabling lint check per tests case should be alright
• all tests should pass
• there should be no lint errors

[emekaokoli19]

@vladopajic From what I understand, the issue here is to add t.parallel() to the test functions in pkg/postage right? Also, how do I enable paralleltest for pkg/postage? Do I make changes to the golangci.yml file?

[vladopajic]

@emekaokoli19 You are right on everything :)