Remove .value from Node protocol.

[tobiasraabe]

• Do not require .value for Node.
• to changes.

Changes

Provide a description and/or bullet points to describe the changes in this PR.

Todo

• Reference issues which can be closed due to this PR with "Closes #x".
• Review whether the documentation needs to be updated.
• Document PR in docs/changes.rst.

[codecov]

Codecov Report

Merging #408 (6d1a59a) into main (449635e) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head 6d1a59a differs from pull request most recent head 33fac11. Consider uploading reports for the commit 33fac11 to get more accurate results

@@            Coverage Diff             @@
##             main     #408      +/-   ##
==========================================
- Coverage   95.66%   95.65%   -0.01%     
==========================================
  Files          94       94              
  Lines        8296     8293       -3     
==========================================
- Hits         7936     7933       -3     
  Misses        360      360              

Flag	Coverage Δ
end_to_end	82.97% <100.00%> (-0.01%)	⬇️
integration	39.56% <71.42%> (-0.03%)	⬇️
unit	65.98% <85.71%> (+0.02%)	⬆️

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Files Changed	Coverage Δ
src/_pytask/node_protocols.py	100.00% <ø> (ø)
tests/test_collect_command.py	100.00% <ø> (ø)
src/_pytask/nodes.py	93.10% <100.00%> (-0.12%)	⬇️