chore: update priority queue to fit new JOBS v2 interface

[rustatian]

Reason for This PR

ref: roadrunner-server/roadrunner#1382

Description of Changes

• Slightly refactor PQ.

License Acceptance

By submitting this pull request, I confirm that my contribution is made under
the terms of the MIT license.

PR Checklist

[Author TODO: Meet these criteria.]
[Reviewer TODO: Verify that these criteria are met. Request changes if not]

• All commits in this PR are signed (git commit -s).
• The reason for this PR is clearly provided (issue no. or explanation).
• The description of changes is clear and encompassing.
• Any required documentation changes (code and docs) are included in this PR.
• Any user-facing changes are mentioned in CHANGELOG.md.
• All added/changed functionality is tested.

[codecov]

Codecov Report

Merging #80 (06f89ad) into master (0dd93ee) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master      #80   +/-   ##
=======================================
  Coverage   82.77%   82.77%           
=======================================
  Files          22       22           
  Lines        1904     1904           
=======================================
  Hits         1576     1576           
  Misses        273      273           
  Partials       55       55           

Impacted Files	Coverage Δ
pool/static_pool/static_pool.go	71.98% <ø> (ø)
priority_queue/monotonic_stack.go	100.00% <ø> (ø)
priority_queue/binary_heap.go	100.00% <100.00%> (ø)