Cannot install libcst extra package

[major]

Environment details

• OS type and version: Fedora 35 (Linux)
• Python version: 3.10.0
• pip version: 21.2.3
• google-cloud-containeranalysis version: HEAD of main branch

Steps to reproduce

1. Run pip install "google-cloud-containeranalysis[libcst]"
2. The libcst extra is not found.

Code example

Not applicable.

Stack trace

➜ pip install -U "google-cloud-containeranalysis[libcst]"
Requirement already satisfied: google-cloud-containeranalysis[libcst] in ./testvenv/lib/python3.10/site-packages (2.6.0)
WARNING: google-cloud-containeranalysis 2.6.0 does not provide the extra 'libcst'

[major]

Thanks, @parthea! 🤗