CI: Access DagsHub repository via an access token

[seisman]

dvc pull started to fail recently with errors like:

2025-09-07 01:23:24,119 DEBUG: v3.63.0 (pip), CPython 3.11.13 on Linux-6.11.0-1018-azure-x86_64-with-glibc2.39
2025-09-07 01:23:24,119 DEBUG: command: /home/runner/work/pygmt/pygmt/.venv/bin/dvc pull --no-run-cache --verbose
2025-09-07 01:23:26,142 DEBUG: Preparing to transfer data from 'https://dagshub.com/GenericMappingTools/pygmt.dvc/files/md5' to '/home/runner/work/pygmt/pygmt/.dvc/cache/files/md5'
2025-09-07 01:23:26,142 DEBUG: Preparing to collect status from '/home/runner/work/pygmt/pygmt/.dvc/cache/files/md5'
2025-09-07 01:23:26,142 DEBUG: Collecting status from '/home/runner/work/pygmt/pygmt/.dvc/cache/files/md5'
2025-09-07 01:23:26,144 DEBUG: Preparing to collect status from 'https://dagshub.com/GenericMappingTools/pygmt.dvc/files/md5'
2025-09-07 01:23:26,144 DEBUG: Collecting status from 'https://dagshub.com/GenericMappingTools/pygmt.dvc/files/md5'
2025-09-07 01:23:26,144 DEBUG: Querying 172 oids via object_exists
2025-09-07 01:23:26,881 WARNING: Some of the cache files do not exist neither locally nor on remote. Missing cache files:
md5: b73351d7d37e5d56fbcab6d46132026a
md5: e4bc1a90f4f25220fe759cdb0a709db8

I still don't know why it failed suddenly, but it turns out that we can fix the dvc issue via an access token.

[Copilot]

Pull Request Overview

This PR addresses DVC (Data Version Control) failures when accessing the DagsHub repository by implementing token-based authentication. The recent failures were occurring when trying to pull baseline image data from the remote repository.

• Configures DVC remote access with an authentication token for all CI workflows
• Updates four GitHub Actions workflow files to use the DAGSHUB_TOKEN secret
• Modifies the DVC remote URL to include token authentication before pulling data

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
.github/workflows/release-baseline-images.yml	Adds token authentication for DVC remote before pulling baseline images
.github/workflows/dvc-diff.yml	Configures DVC remote with token and adds environment variable
.github/workflows/ci_tests_dev.yaml	Updates development CI to use authenticated DVC remote access
.github/workflows/ci_tests.yaml	Updates main CI to use authenticated DVC remote access

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[weiji14]

Cheers for figuring this out! Pity that we can't access things publicly now.