cherrypick script ran out of buffer using exec

Ran into this problem when trying to cherrypick

```
node:child_process:965
throw err;
^

Error: spawnSync /bin/sh ENOBUFS
at Object.spawnSync (node:internal/child_process:1124:20)
at spawnSync (node:child_process:876:24)
at execSync (node:child_process:957:15)
at getCommits (/Users/stevenlambert/deque/axe-core/build/cherry-pick.js:52:18)
at Object. (/Users/stevenlambert/deque/axe-core/build/cherry-pick.js:113:29)
at Module._compile (node:internal/modules/cjs/loader:1358:14)
at Module._extensions..js (node:internal/modules/cjs/loader:1416:10)
at Module.load (node:internal/modules/cjs/loader:1208:32)
at Module._load (node:internal/modules/cjs/loader:1024:12)
at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:174:12) {
errno: -55,
code: 'ENOBUFS',
syscall: 'spawnSync /bin/sh',
path: '/bin/sh',
spawnargs: [ '-c', 'git log develop --abbrev-commit --since=2022' ],
error: [Circular *1],
status: null,
signal: 'SIGTERM',
output: [
```

Looks like the call to `git log` exceeded the buffer size limit of `exec`. We could fix this in a few different ways. Either we switch to use `spawn` instead of `exec` and update the code accordingly to handle streaming data, or we could increase the buffer limit of `exec` for certain calls (like `git log`), or reduce the amount of time to get commits from (2 years instead of 3).