Cabal init doesn't honour multiple --dependency flags

[fendor]

Describe the bug
cabal init --lib -d base -d vector should create a cabal file containing both of these dependencies.

To Reproduce
Steps to reproduce the behavior:

$ cabal init --lib -d base -d vector
$ cat test.cabal
...
    build-depends:    vector

but I'd expect:

$ cabal init --lib -d base -d vector
$ cat test.cabal
...
    build-depends:    base, vector

System information

• cabal 3.6, cabal 3.8 and cabal HEAD

[fendor]

Looking at the code-base, it seems like all occurrences of Flag [..] don't behave as intended in the option parser.
Time to document the parser >.<