Add missing property in MRR

[VincentLanglet]

Hi @pkopac @sbrych,

I received tons of deprecations:

Deprecated: Creation of dynamic property ChartMogul\Metrics\MRR::$percentage_change is deprecated

According to the API reference the property $percentage_change exists
https://dev.chartmogul.com/reference/retrieve-mrr
So I added it to the class. It would be great if you have time to merge and release this. :)

I dunno if it was a miss or if the data was recently added to the API.
But if you're regularly adding new value in API response, you might want to add the #[AllowDynamicProperties] to the AbstractModel class in order to avoid any deprecations in the futur.

[VincentLanglet]

Friendly ping @pkopac @sbrych, any time to take a look ? :)

[pkopac]

Hello @VincentLanglet! Thank you for the PR and sorry about the delay, I missed it completely until you pinged us. We'll look into adding AllowDynamicProperties it sounds useful.

[VincentLanglet]

Hello @VincentLanglet! Thank you for the PR and sorry about the delay, I missed it completely until you pinged us. We'll look into adding AllowDynamicProperties it sounds useful.

No problem, I pinged just in case ^^ ; if you have time for a patch release it would be perfect for me.

[pkopac]

@VincentLanglet 👍 https://github.com/chartmogul/chartmogul-php/releases/tag/v5.1.1