strings: `enter-bios` is not technically correct

[zefr0x]

cosmic-osd/i18n/en/cosmic_osd.ftl

Line 8 in e58340f

enter-bios = Enter BIOS

I know that most people just call it BIOS anyway, but it's not technically correct in all cases. In most modern systems it would be UEFI.

I believe it would be better if we had a generic name for this (e.g. Firmware Settings, Hardware Settings, ...) or we detect if the system uses BIOS or UEFI and use a different strings.

Note that the first option is better for i18n.