kernelctl should no longer use /etc/version

[Eeems]

Describe the issue
Kernelctl uses /etc/version when creating a backup of the current kernel. As this stops being a unique value in newer OS builds,

To Reproduce
Steps to reproduce the behaviour:

1. install kernelctl
2. run kernelctl list to see list of kernels

Expected behaviour
It should be using RELEASE_VERSION from /usr/share/remarkable/update.conf for the OS version number instead.

Upstream issue
N/A

Screenshots

System information:

• toltecctl status output: N/A
• Package: kernelctl

Additional context
toltecctl has the following code available that kernelctl could call:

toltec/package/toltec-bootstrap/toltecctl

Lines 108 to 110 in eed41f1

	get-release-version() {
	awk -F= '/RELEASE_VERSION/{print $2}' /usr/share/remarkable/update.conf
	}

[Eeems]

@Etn40ff would you be willing to make this change?

[Etn40ff]

@Etn40ff would you be willing to make this change?

Sure