Ensure number strings are treated as HTML

[daun]

• A pure number string like 1999 will currently be interpreted as valid JSON
• This will fail in subsequent steps because a JSON object/array is expected, instead of the number 1999
• This change will mark any string starting with a number as HTML going forward
• An alternative could be to expect { or [ as first character to mark things as JSON
• I've added a test, but can't get it to run locally because of PHP deprecations in Pest :(

[manojhl]

I agree with this change, thanks for fixing this! I also need this behavior in my projects, so looking forward to it being merged.

[mtozzo]

I've fixed similar issues in my wrapper for this library for strings such as null and false in addition to numbers. I'm currently trying to figure out how to prevent a crash if the input is just an HTML comment such as <!-- This is a comment that should be ignored -->.