fix doc workflow

[epassaro]

Description

Update setup-miniconda action to v2.

Motivation and Context

Documentation build pipeline recently failed because some recent changes in GitHub Actions.

Using the solution from conda-incubator/setup-miniconda#101

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have assigned/requested two reviewers for this pull request.

[codecov]

Codecov Report

Merging #1353 (a2c6169) into master (cda41f1) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1353   +/-   ##
=======================================
  Coverage   71.24%   71.24%           
=======================================
  Files          66       66           
  Lines        5077     5077           
=======================================
  Hits         3617     3617           
  Misses       1460     1460           

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