fix: Remove PTR from _include_change

[thierrycourtois]

Hello,

I would like to synchronise PTR record from infoblox to netbox but unfortunately I have the following issue:
DEBUG NetBoxDNSProvider[netbox_preprod] record not supported as provider, ignoring: <PtrRecord PTR 300, 1.1.1.1.in-addr.arpa., ['tcs.tcs.']>

I guess this issue is related to the function _include_change.

I tested the change submitted in this PR with the following infrastructure without issue:

• netbox version: 3.7.8
• netbox DNS plugin version 0.22.8

Here is the result
2025-02-12T14:36:16 [139906302902272] DEBUG Zone changes: zone=Zone<1.1.1.in-addr.arpa.>, create record=<PtrRecord PTR 300, 1.1.1.1.in-addr.arpa., ['tcs.tcs.']>
2025-02-12T14:36:16 [139906302902272] DEBUG Plan init: Creates=1, Updates=0, Deletes=0 Existing=0
2025-02-12T14:36:16 [139906302902272] INFO NetBoxDNSProvider[netbox_preprod] plan: Creates=1, Updates=0, Deletes=0, Existing Records=0
2025-02-12T14:36:16 [139906302902272] INFO Plan
1.1.1.in-addr.arpa.
netbox_preprod (NetBoxDNSProvider)
Create <PtrRecord PTR 300, 1.1.1.1.in-addr.arpa., ['tcs.tcs.']> (infoblox)
Summary: Creates=1, Updates=0, Deletes=0, Existing Records=0

Could you explain me why this function has been include in this plugin in version v0.3.4?

Thank you for your time