NetMon v1.5.1

Auto-increment the release patch version instead of failing

NetMonGui.csproj's <Version> is now the "intended" minor version (bump
it only when you actually want a new one) - every push that doesn't
change it now auto-increments the patch digit by checking existing
release tags (v1.5.0 -> v1.5.1 -> v1.5.2, ...), rather than vpk just
failing loudly because that exact version's tag already exists.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>