Doesn't work with the `--profile` flag.

[cessen]

I'd like to release development builds of my application with debug information included, so that people can more easily help me track down bugs that they've reported. So I've made a custom build profile called "release-debug".

However, trying to specify it as the build mode results in this:

$ cargo appimage --profile=release-debug
error: conflicting usage of --profile=release-debug and --release
The `--release` flag is the same as `--profile=release`.
Remove one flag or the other to continue.

It appears that cargo-appimage unconditionally passes the --release flag, which conflicts with --profile