Fix PhpComposerLock parser error by supporting non-string versions

What does this MR do and why?

Background

The Repository X-Ray scans a project's repository for dependency config files and then parses a list of libraries from the file content. The libraries are then included into the code generation prompt to improve code suggestions. This feature was converted from a CI job to an internal Sidekiq job, and is currently rolled out at 100% in #483928.

This MR

While monitoring the Sidekiq failed job logs, we noticed the following error:

• json.exception.class: NoMethodError
• json.exception.message: undefined method `delete_prefix' for 20240308:Integer

This error occurs because delete_prefix is being called on an Integer instead of a String in PhpComposerLock here.

In this MR, we handle the error so that it doesn't bubble up as a Sidekiq job error. Specifically, we:

• Updated PhpComposerLock parsing logic with a try on delete_prefix so that it doesn't raise an exception. If the value is a non-string, it falls through to the base class sanitize_libs method.
• Updated the base class sanitize_libs so that it converts any valid version data type to a string before handling.
  • It's assumed that a valid version may sometimes be specified as an Integer or Float within structured data formats like JSON.
  • Making this change in the base class allows us to cover all config file types where this could occur.

MR acceptance checklist

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Screenshots or screen recordings

Error reproduced locally with new spec test	Spec test passes after change

Related to #483928