Implement fixer

[firelizzard18]

Updates the analyzer to support automatic fixes for golangci-lint.

Updates #2.

[firelizzard18]

@denis-tingaikin

[denis-tingaikin]

@firelizzard18 Woot! Looks good. Let me test it a bit.

[denis-tingaikin]

@firelizzard18 It also seems like unit tests detect SIGSEGV. https://github.com/denis-tingaikin/go-header/actions/runs/7561279933/job/21541496704?pr=36

Could you have a look? 

I've added an assignee to myself to get notifications; feel free to ping me inside PR when it is fixed.

[firelizzard18]

@denis-tingaikin I fixed the panic. I'm not sure why I had written if i.Message() == "", that clearly was not the right condition...

TestAnalyzer_YearRangeValue_ShouldWorkWithComplexVariables is failing on main with the same error, so I don't think that's something I broke. I also added TestFix to verify that a fix is actually produced and produced in the correct way. I have manually verified that my changes work with golangci-lint, and work for all the cases I could think of in terms of how the header comment is structured.

[denis-tingaikin]

As I can see we have only one problem with a test.

It's related to oudated input for the expected value here https://github.com/denis-tingaikin/go-header/blob/main/analyzer_test.go#L57

that we can fix with something like this:

---require.Nil(t, a.Analyze(header(`A 2000-2022 B`)))
+++require.Nil(t, a.Analyze(header(fmt.Sprintf("A 2000-%v B", time.Now().Year()))))

[firelizzard18]

@denis-tingaikin I applied the fix for the test

[denis-tingaikin]

@firelizzard18 Great work! Merging..