Update deprecated GitHub actions

[giffels]

This pull request addresses potential warnings about the migration of GitHub actions from nodejs:12 to nodejs:16.

Like

Node.js 12 actions are deprecated. Please update the following actions to use Node.js 16: actions/checkout@v2,
actions/setup-python@v2, codecov/codecov-action@v1. 
For more information see: 
https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/.

Fixes issue with missing Python 3.6 on ubuntu:latest (see actions/runner-images#6399).

[codecov]

Codecov Report

Base: 92.91% // Head: 92.73% // Decreases project coverage by -0.18% ⚠️

Coverage data is based on head (c1003e2) compared to base (0343272).
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #118      +/-   ##
==========================================
- Coverage   92.91%   92.73%   -0.18%     
==========================================
  Files          34       34              
  Lines        1143     1143              
  Branches      166      166              
==========================================
- Hits         1062     1060       -2     
- Misses         59       60       +1     
- Partials       22       23       +1     

Impacted Files	Coverage Δ
src/cobald/daemon/runners/trio_runner.py	94.64% <0.00%> (-3.58%)	⬇️

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[maxfischer2781]

Do you need to make any more changes to this? I'm fine with merging this otherwise.

[giffels]

No. Please, merge.