cargo: Update dependencies

[felinira]

Replace xsalsa20poly1305 with crypto_secretbox: https://rustsec.org/advisories/RUSTSEC-2023-0037.html
Update webpki: https://rustsec.org/advisories/RUSTSEC-2023-0052.html

Closes #204 #197

[codecov]

Codecov Report

Patch coverage: 69.23% and project coverage change: -0.24% ⚠️

Comparison is base (8f379b7) 40.52% compared to head (d577f3b) 40.29%.

❗ Current head d577f3b differs from pull request most recent head 7810529. Consider uploading reports for the commit 7810529 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #205      +/-   ##
==========================================
- Coverage   40.52%   40.29%   -0.24%     
==========================================
  Files          23       23              
  Lines        3326     3318       -8     
==========================================
- Hits         1348     1337      -11     
- Misses       1978     1981       +3     

Files Changed	Coverage Δ
src/core.rs	72.92% <ø> (-1.27%)	⬇️
src/util.rs	31.91% <0.00%> (-5.20%)	⬇️
src/core/key.rs	98.61% <100.00%> (ø)
src/core/server_messages.rs	67.64% <100.00%> (ø)
src/transit/crypto.rs	41.84% <100.00%> (-1.42%)	⬇️

... and 4 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[felinira]

According to CI this needs an MSRV bump to 1.67

https://github.com/magic-wormhole/magic-wormhole.rs/actions/runs/6136864340/job/16652120206#step:6:140

error: package `time v0.3.28` cannot be built because it requires rustc 1.67.0 or newer, while the currently active rustc version is 1.66.0

[felinira]

1.70, even. Why can't it tell me in the first place, oh well.

error: package `async-tungstenite v0.23.0` cannot be built because it requires rustc 1.70 or newer, while the currently active rustc version is 1.67.0

[piegamesde]

Thank you