[ENH] Updated HED Version to 8.4.0 in examples

[VisLab]

Updated specification to use latest HED version in the examples.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.71%. Comparing base (d62a5d2) to head (2a36d0c).
⚠️ Report is 69 commits behind head on master.

Additional details and impacted files

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  Coverage   82.71%   82.71%           
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  Files          20       20           
  Lines        1608     1608           
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  Hits         1330     1330           
  Misses        278      278           

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[yarikoptic]

2 approvals, I will merge. but I am curious

• was that necessary for anything @VisLab ?
• are you planing to perform similar upgrades in the future just to point to more recent version?
• should we strive to make it some form of a "convention" or do the opposite and point to minimal compatible version or ...
  ?

[VisLab]

@yarikoptic @effigies The reason that it is important to revise the examples to the latest version of HED is that these are EXAMPLES. This means that people hopefully use them as models when putting their dataset into BIDS. These examples should be continually updated to show best practices and the latest versions. Some of the examples both in the Examples and the Specification have ancient values of BIDS also. BTW, We don't release new versions of HED very often (usually more than a year between releases).

2 approvals, I will merge. but I am curious

* was that necessary for anything @VisLab ?

* are you planing to perform similar upgrades in the future just to point to more recent version?

* should we strive to make it some form of a "convention" or do the opposite and point to minimal compatible version or ...
  ?