Use stable Swashbuckle for tests because the latest version on dev-feed is currently broken

Author: bkoelman

package-versions.props

@@ -27,7 +27,7 @@
     <PolyfillVersion>9.3.*</PolyfillVersion>
     <ReadableExpressionsVersion>4.1.*</ReadableExpressionsVersion>
     <ScalarAspNetCoreVersion>2.11.*</ScalarAspNetCoreVersion>
-    <SwashbuckleVersion>10.*-*</SwashbuckleVersion>
+    <SwashbuckleVersion>$(SwashbuckleFrozenVersion)</SwashbuckleVersion>
     <SystemTextJsonVersion>10.0.*</SystemTextJsonVersion>
     <TestSdkVersion>18.0.*</TestSdkVersion>
     <XunitVersion>2.9.*</XunitVersion>