Bump to firtool 1.38.0

[jackkoenig]

Contributor Checklist

• [NA] Did you add Scaladoc to every public function/method?
• Did you add at least one test demonstrating the PR?
• Did you delete any extraneous printlns/debugging code?
• Did you specify the type of improvement?
• Did you add appropriate documentation in docs/src?
• Did you request a desired merge strategy?
• Did you add text to be included in the Release Notes for this change?

Type of Improvement

• Dependency update

Desired Merge Strategy

• Squash

Release Notes

See firtool release notes.

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels? (Select the most appropriate one based on the "Type of Improvement")
• Did you mark the proper milestone (Bug fix: 3.5.x or 3.6.x depending on impact, API modification or big change: 5.0.0)?
• Did you review?
• Did you check whether all relevant Contributor checkboxes have been checked?
• Did you do one of the following when ready to merge:
  • Squash: You/ the contributor Enable auto-merge (squash), clean up the commit message, and label with Please Merge.
  • Merge: Ensure that contributor has cleaned up their commit history, then merge with Create a merge commit.

[jackkoenig]

It seems firtool's command-line arguments used by Chisel have changed again. In concert with asking the firtool devs to exercise a little more discretion in changing them, we should handle some amount of decoupling in Chisel as well. We can detect and adjust our command-line arguments based on the firtool version.

The bigger issue is how to test against multiple versions without blowing up CI compute needs. At least CI is a bit faster now--it may be worth backporting those changes to 3.6.x which probably ought to be tested against multiple firtool versions.

[jackkoenig]

Not backporting this, firtool 1.38.0 support for the 3.6.x line will be done separately.