I appreciate you took the time to create this PR.
I've tried it on Ubuntu and it works great!

FYI below. I do not consider this needs documenting; if the admin has pinned the kernel version as described below then presumably they are an advanced user and can react accordingly.

An edge-case downside of this approach is present when kernel versions are managed externally and the administrator chooses to pin an older version, such as with Proxmox;

jeremy@pve:~$ sudo uname -r
6.17.13-7-pve

jeremy@pve:~$ sudo proxmox-boot-tool kernel list
Manually selected kernels:
None.

Automatically selected kernels:
6.17.13-7-pve
7.0.2-2-pve

Pinned kernel:
6.17.13-7-pve

jeremy@pve:~$ sudo needrestart -p
CRIT - Kernel: 6.17.13-7-pve!=7.0.2-2-pve (!!), Microcode: CURRENT, Services: none, Containers: none, Sessions: none|Kernel=2;0;;0;2 Microcode=0;0;;0;1 Services=0;;0;0 Containers=0;;0;0 Sessions=0;0;;0

It is recommended to always manually inspect the details: attribute of the Required Restart sensor to determine the cause of the Positive result, and react based on content.

To direct needrestart to ignore your pinned kernel version, create a drop-in file in /etc/needrestart/conf.d/ with the directive $nrcon{kernelfilter}:

root@pve:~# cat /etc/needrestart/conf.d/10-kernel-pin.conf
$nrconf{kernelfilter} = qr(vmlinuz-6\.17\.13-7-pve);

Note the use of regex, so . characters must be escaped. The filter is inclusive so will not alert to the exact specified value, but will alert to anything else. Adjust the content of this file each time you change the pinned version, and delete the file when you remove the kernel pin.