chore: rename "Punit" to "PUnit" in definitions

[grunweg]

The previous names were simply wrong. Reported on zulip.

---

[github-actions]

PR summary 8115783e28

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

---

Declarations diff

+ actionPUnitEquivalence
+ freeCommRingPUnitEquivPolynomialInt
+ freeRingPUnitEquivPolynomialInt
+ isTerminalPUnit
+ pemptyToPUnit
+ prodPUnit
+ specPUnitIsInitial

You can run this locally as follows

## summary with just the declaration names:
./scripts/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/declarations_diff.sh long <optional_commit>

The doc-module for script/declarations_diff.sh contains some details about this script.

---

No changes to technical debt.

You can run this locally as

./scripts/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).