[chloggen] Disallow whitespace-only values

[djaglowski]

Resolved #164

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (7df0c50) 60.22% compared to head (3be09a1) 60.22%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #239   +/-   ##
=======================================
  Coverage   60.22%   60.22%           
=======================================
  Files          47       47           
  Lines        2172     2172           
=======================================
  Hits         1308     1308           
  Misses        721      721           
  Partials      143      143           

Impacted Files	Coverage Δ
chloggen/internal/chlog/entry.go	76.92% <100.00%> (ø)

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[djaglowski]

Closing as duplicate of #165

[pellared]

@djaglowski If you want you can reopen it as #165 got stale and I closed it.