version: add concurrency on update checks

General MR

Summary

Update code to check for upstream updates concurrently.

Relevant logs/screenshots

Benchmarks:

Non-concurrent

Benchmark 1: bbctl version --all-charts --check-for-updates
  Time (mean ± σ):      5.096 s ±  0.482 s    [User: 0.310 s, System: 0.052 s]
  Range (min … max):    4.626 s …  6.119 s    10 runs

Concurrent

Benchmark 1: bbctl version --all-charts --check-for-updates
  Time (mean ± σ):      2.535 s ±  0.620 s    [User: 0.325 s, System: 0.057 s]
  Range (min … max):    2.054 s …  3.724 s    10 runs

Linked Issue

Suggested by Andrew here: !183 (comment 2483381)

Upgrade Notices

N/A