Update dependencies

[talex5]

• Use opam-0install 0.4.4 to fix possible race
• Use opam.dev for faster opamVersionCompare

On my machine, I get:

Solved 10 requests in 18.08s (1.81s/iter) (8.85 solves/s)   # Before
Solved 10 requests in 14.39s (1.44s/iter) (11.12 solves/s)  # After

[talex5]

On jade-2 with 8 workers, it went from 4 solves/s to 7.

Tested as in the README:

opam@8a4cbc0b423a:/src$ dune exec -- solver-service run-service     --cache-dir=./cache     --capnp-secret-key-file=server.pem     --capnp-listen-address=tcp:127.0.0.1:7000     --cap-file=./capnp-secrets/solver.cap --internal-workers=8
opam@1de67f414d6a:/src$ dune exec -- ./stress/stress.exe service ./capnp-secrets/solver.cap --count=10