Remove singularity settings from cannon.config

[microlei]

Removed singularity configuration from cannon.config. Some workflows use conda, and forcing singularity across the board is not optimal.

---

name: New Config
about: A new cluster config

Please follow these steps before submitting your PR:

• If your PR is a work in progress, include [WIP] in its title
• Your PR targets the master branch
• You've included links to relevant issues, if any

Steps for adding a new config profile:

• Add your custom config file to the conf/ directory
• Add your documentation file to the docs/ directory
• Add your custom profile to the nfcore_custom.config file in the top-level directory
• Add your profile name to the profile: scope in .github/workflows/main.yml
• OPTIONAL: Add your custom profile path and GitHub user name to .github/CODEOWNERS (**/<custom-profile>** @<github-username>)

[pontus]

Approved, but the reason seems very confusing - since this is an nf-core config, what pipeline doesn't work with singularity? My guess is this change will lead to more issues.

[microlei]

I've been encouraging people to use this for third party nextflow pipelines as well.