Remove workaround for CVXOPT binaries on Python 3.14

### Context https://github.com/nextstrain/augur/blob/1a164ff998e6e4614c602192e83fc7b72d0b3e53/.github/workflows/ci.yaml#L75-L78 ### Steps 1. Wait for [Python 3.14 binaries for `cvxopt` on PyPI](https://github.com/cvxopt/cvxopt/issues/265) 2. Remove cvxopt from the `create-args` above and revert 66b64b25a86a34ae84402a6f90c487104b0bf54d