Support for underscores as a just digit separators

[painhardcore]

Describe the bug
Currently, if somewhere we have in code:

const SomeVeryImportantThing = 1_000_000

We'll have warning in the console on the executing

warning: failed to evaluate const defaultMaxWriteSize at /google/secret_project/money.go:17:7, strconv.ParseUint: parsing "1_000_000": invalid syntax

The problem is that you should base 0 when you use strconv.ParseUint .

To Reproduce
Steps to reproduce the behavior:

1. Make a constant with underscore
2. Execute swag tooling
3. See the warning in the output

Expected behavior
I don't expect any warning/error related to the valid constants

Your swag version
swag version v1.8.12

Your go version
go version go1.20.3 darwin/arm64

Desktop (please complete the following information):

• OS: MacOS
• Browser: not relevant
• Version: not relevant