Add compare_release fast path (#799)
Looking at the profile for tf-models-nightly after #789,
`compare_release` is the single biggest item. Adding a fast path, we
avoid paying the cost for padding releases with 0s when they are the
same length, resulting in a 16% for this pathological case. Note that
this mainly happens because tf-models-nightly is almost all large dev
releases that hit the slow path.
**Before**
**After**
```
$ hyperfine --warmup 1 --runs 3 "target/profiling/main pip-compile -q scripts/requirements/tf-models-nightly.txt"
"target/profiling/puffin pip-compile -q scripts/requirements/tf-models-nightly.txt"
Benchmark 1: target/profiling/main pip-compile -q scripts/requirements/tf-models-nightly.txt
Time (mean ± σ): 11.963 s ± 0.225 s [User: 11.478 s, System: 0.451 s]
Range (min … max): 11.747 s … 12.196 s 3 runs
Benchmark 2: target/profiling/puffin pip-compile -q scripts/requirements/tf-models-nightly.txt
Time (mean ± σ): 10.317 s ± 0.720 s [User: 9.885 s, System: 0.404 s]
Range (min … max): 9.501 s … 10.860 s 3 runs
Summary
target/profiling/puffin pip-compile -q scripts/requirements/tf-models-nightly.txt ran
1.16 ± 0.08 times faster than target/profiling/main pip-compile -q scripts/requirements/tf-models-nightly.txt
```
