• This is a bug report
• This is a feature request
• I searched existing issues before opening this one

Expected behavior

LABEL org.opencontainers.image.authors="Me"   # passed DL3048 check
LABEL my.label/with_underscore="Illegal underscore and slash"   # should pass the DL3048 check

Actual behavior

Slashes and Underscores are not accepted in the LABEL key.
The following definition should pass but is reported as a failure:

LABEL my.label/with_underscore="Illegal underscore and slash"  

Steps to reproduce the behavior

See above

This is expected, since the code of DL3048 defines the allowed characters.
See https://hackage.haskell.org/package/hadolint-2.12.0/docs/src/Hadolint.Rule.DL3048.html#containsIllegalChar
specifically the line:

validChars = ['0'..'9'] ++ ['a' .. 'z'] ++ ['.', '-']

PR: #1034

Output of hadolint --version or
docker run --rm hadolint/hadolint hadolint --version or
docker run --rm ghcr.io/hadolint/hadolint hadolint --version:

2.12.0

Additional environment details (OS, stack version, etc.)