update test ctlog validFor period in trusted root

[bdehamer]

Per #616

Summary

Updating the trusted_root.json target with the correct valid-for range on the "https://ctfe.sigstore.dev/test" ctlog entry.

In an effort to get better start/end dates, I examined the first and last entries on the "test" ctlog and looked at the corresponding timestamps:

curl "https://ctfe.sigstore.dev/test/ct/v1/get-entries?start=0&end=0"
curl "https://ctfe.sigstore.dev/test/ct/v1/get-entries?start=3533286&end=3533286"

I found the first and last timestamps to be "2021-03-14T16:27:21.940Z" and "2022-10-31T19:29:48.033Z"

When setting the valid-for range for the corresponding ctlog key, I rounded that first timestamp down to the beginning of the day and rounded the last timestamp up to the end of the day.

(@haydentherapper am I on the right track here?)

[kommendorkapten]

I think this looks good but would like to hear from @haydentherapper before merging.

[haydentherapper]

Thanks for checking! This looks good.