Fix behavior change for createCompounder when deburring is not enabled

[ElMassimo]

Found the problem through Webpack non-deterministic builds as described in #162, this pull request fixes a change in behavior in all functions that depend on createCompounder when deburring is not enabled:

• camelCase
• kebabCase
• lowerCase
• snakeCase
• startCase
• upperCase

Assuming these functions are expected to work with non-String arguments, such as null or {}, since that's the behavior in the full build of the library.

The Bug 🐞

When deburring is disabled, deburr will be replaced with identity, failing to coerce the argument to a String as it normally would, so createCompounder fails when calling replace if the function was called with any non-String argument.

The Fix 🔨

Substitute deburr with toString instead when deburring is disabled. This will ensure any arguments are coerced as usual, but no regex replacement will occur.

[jsf-clabot]

All committers have signed the CLA.

[jdalton]

Thank you @ElMassimo!