Update CI to fix deprecation issues, update dev install instructions

[rly]

Motivation

Fix #1567
Fix #1589
Fix other deprecations in GitHub Actions

Checklist

• Did you update CHANGELOG.md with your changes?
• Have you checked our Contributing document?
• Have you ensured the PR clearly describes the problem and the solution?
• Is your contribution compliant with our coding style? This can be checked running flake8 from the source directory.
• Have you checked to ensure that there aren't other open Pull Requests for the same change?
• Have you included the relevant issue number using "Fix #XXX" notation where XXX is the issue number? By including "Fix #XXX" you allow GitHub to close issue #XXX when the PR is merged.

[codecov]

Codecov Report

Merging #1594 (668c61b) into dev (c1afdc1) will decrease coverage by 0.09%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##              dev    #1594      +/-   ##
==========================================
- Coverage   91.28%   91.19%   -0.10%     
==========================================
  Files          25       25              
  Lines        2502     2510       +8     
  Branches      472      474       +2     
==========================================
+ Hits         2284     2289       +5     
- Misses        138      140       +2     
- Partials       80       81       +1     

Flag	Coverage Δ
integration	70.35% <ø> (-0.03%)	⬇️
unit	84.42% <ø> (-0.04%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/pynwb/io/misc.py	82.05% <0.00%> (-4.80%)	⬇️
src/pynwb/ecephys.py	95.49% <0.00%> (-0.87%)	⬇️
src/pynwb/base.py	100.00% <0.00%> (ø)
src/pynwb/io/epoch.py	100.00% <0.00%> (ø)

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