allow OrdinaryDiffEq.jl v6

[ranocha]

Closes #1020; closes #1021; closes #1022

[codecov]

Codecov Report

Merging #1023 (ba96269) into main (f958b8e) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1023   +/-   ##
=======================================
  Coverage   94.04%   94.04%           
=======================================
  Files         288      288           
  Lines       22444    22444           
=======================================
  Hits        21106    21106           
  Misses       1338     1338           

Flag	Coverage Δ
unittests	94.04% <ø> (ø)

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

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update f958b8e...ba96269. Read the comment docs.