Remove Spyder version in conda create command

[jitseniesen]

Pull Request

Pull Request Checklist

• [x] Read and followed this repo's Contributing Guidelines
• [x] Based your PR on the latest version of the correct branch (master or 4.x)
• [x] Checked your writing carefully for correct English spelling, grammar, etc
• [x] Described your changes and the motivation for them below
• [x] Noted what issue(s) this pull request resolves, creating one if needed

Description of Changes

I don't know why the version number was specified, but it should probably be updated with every major release or removed. The latter option seems the simplest.

Issue(s) Resolved

Fixes #313

[CAM-Gerlach]

We need to pin the Jinja version to avoid an incompatibility with Sphinx 3, something which I should have done a while ago, sorry. I'll open a PR to fix it, hold on...

[CAM-Gerlach]

I've fixed everything in #315 triggered an auto-updated of your branch with GitHub's new Update Branch button, so this should be good to go.