Make the --bind option optional

[webbnh]

This PR removes the "prompt" requirement from the --bind option configuration, so that, if the option is omitted from the command line, the default value will be silently used, rather than requiring the user to confirm it.

This was originally part of #7, but, while it is important for the effectiveness of that change, it doesn't really have anything to do containerization; and, since I had to rebase it on top of #8 anyway, I figured I would split it out into it's own PR. Note that this PR is layered on top of #9, so until it is merged, its commit(s) (and those of #8) will show up here; so, for this review, only the last commit (so far) should be considered.

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (9655b23) 98.52% compared to head (19f7c6a) 98.52%.

❗ Current head 19f7c6a differs from pull request most recent head 82ad46a. Consider uploading reports for the commit 82ad46a to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #10   +/-   ##
=======================================
  Coverage   98.52%   98.52%           
=======================================
  Files           2        2           
  Lines         541      541           
=======================================
  Hits          533      533           
  Misses          8        8           

Files Changed	Coverage Δ
src/relay/relay.py	100.00% <100.00%> (ø)
tests/test_relay.py	97.95% <100.00%> (ø)

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The merge-base changed after approval.