Feature dtcenter/MET#2796 GHA Node20 deprecation warnings

[georgemccabe]

Change Summary

Updates GHA action versions to switch from node 16 to 20 (see issue for shell commands):

1. checkout@v3 -> checkout@v4
2. upload-artifact@v3 -> upload-artifact@v4
3. download-artifact@v3 -> download-artifact@v4
4. setup-python@v4 -> setup-python@v5
5. actions/github-script@v6 -> actions/github-script@v7

Also changed arguments for workflow_dispatch event in testing.yml so that no arguments are required to run. These arguments are set when the workflow is triggered by another repository to include important information about who/what triggered the workflow, but it is not required when triggering the workflow by hand in the GHA web interface. Without this changes, dummy values must be entered to run a workflow by hand, which is unnecessary and time consuming.

Pull Request Testing

• [X] Describe testing already performed for these changes:
  

See MET PR: dtcenter/MET#2797

• [X] Recommend testing for the reviewer(s) to perform, including the location of input datasets, and any additional instructions:
  

Check to make sure all deprecation warnings have gone away

• [X] Do these changes include sufficient documentation updates, ensuring that no errors or warnings exist in the build of the documentation? [Yes]

• [X] Do these changes include sufficient testing updates? [Yes]

• [X] Will this PR result in changes to the test suite? [No]
  

• [X] Please complete this pull request review by 1/26/2024.
  

Pull Request Checklist

See the METplus Workflow for details.

• [X] Add any new Python packages to the METplus Components Python Requirements table.
• [X] Review the source issue metadata (required labels, projects, and milestone).
• [X] Complete the PR definition above.
• [X] Ensure the PR title matches the feature or bugfix branch name.
• [x] Define the PR metadata, as permissions allow. Select: Reviewer(s) Select: Organization level software support Project or Repository level development cycle Project Select: Milestone as the version that will include these changes
• [x] After submitting the PR, select the :gear: icon in the Development section of the right hand sidebar. Search for the issue that this PR will close and select it, if it is not already selected.
• [ ] After the PR is approved, merge your changes. If permissions do not allow this, request that the reviewer do the merge.
• [ ] Close the linked issue and delete your feature or bugfix branch from GitHub.

[coveralls]

Pull Request Test Coverage Report for Build 7645727937

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• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 90.762%

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Totals
Change from base Build 7644931175:	0.0%
Covered Lines:	8508
Relevant Lines:	9374

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💛 - Coveralls