feat: execute could receive a function

[s3xysteak]

Description

The PR makes execute option could receive a function.

pnpm bumpp --execute="echo foo"

export defualt defineConfig({
  execute: 'echo foo'
})

It does not change the before behavior. But it makes users could pass a function in bump.config.ts:

export defualt defineConfig({
  // execute: 'echo foo'

  execute: (config) => {
    console.log('bar', config.results.newVersion)
    // also could be an async function
  }
})

Linked Issues

Closes #53. Related #10.

Additional context

The log messages may need improvement:
src/version-bump.ts

console.log(` execute ${c.bold(typeof operation.options.execute === 'function' ? 'function' : operation.options.execute)}`)