deps: bump Kuestenlogik.Bowire to 1.6.0

Pulls in the v1.6.0 release wave from the main Bowire repo
(plugin-lifecycle panel + REST endpoints + --prerelease CLI flag +
command-injection security fix #39 + bundled-plugin manage view).
No plugin-side code change here, just the floor pin.

Author: thomas-stegemann

Directory.Packages.props

@@ -9,7 +9,7 @@
          interface. During local development consume from
          ../Bowire/artifacts/packages (see nuget.config); release
          builds resolve the same id from nuget.org. -->
-    <PackageVersion Include="Kuestenlogik.Bowire" Version="1.5.1" />
+    <PackageVersion Include="Kuestenlogik.Bowire" Version="1.6.0" />
 
     <!-- Test-only -->
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.5.1" />