stream: prepare 0.1.16 release

[djc]

As discussed on Discord. Full changelog (I skipped most of the chores for the changelog):

djc-2021 stream-0.1.16-prep tokio-stream $ git log --oneline -20 . 
a9fd3b94 (HEAD -> stream-0.1.16-prep, origin/stream-0.1.16-prep) stream: prepare 0.1.16 release
12b2567b (origin/master, origin/HEAD, master) chore: use `poll_fn` from std (#6810)
11f66f43 chore: replace `ready!` with `std::task::ready!` (#6804)
15cd5146 chore: increase MSRV to 1.70 (#6645)
c8f3539b stream: make stream adapters public (#6658)
3a6fdc05 license: fix formatting and remove year in licenses (#6451)
daa89017 ci: fix new clippy warnings (#6569)
2a0df5fb ci: bump nightly to nightly-2024-05-05 (#6538)
be9328da chore: fix clippy warnings (#6466)
a1acfd8c readme: add readme for tokio-stream (#6456)
4601c847 stream: add `next_many` and `poll_next_many` to `StreamMap` (#6409)
7cfb1007 (tag: tokio-stream-0.1.15) chore: prepare tokio-stream v0.1.15 (#6401)

0.1.16 (September 5th, 2024)

This release bumps the MSRV of tokio-stream to 1.70.

• stream: add next_many and poll_next_many to StreamMap (#6409)
• stream: make stream adapters public (#6658)
• readme: add readme for tokio-stream (#6456)

[Darksonn]

Thank you.