Fix SPM build

Author: n8chur

Diff for: Package.swift

@@ -240,6 +240,7 @@ let package = Package(
 
         .target(
             name: "ViewEnvironmentUI",
+            dependencies: ["ViewEnvironment"],
             path: "ViewEnvironmentUI/Sources"
         ),
     ],

Diff for: ViewEnvironmentUI/Sources/ViewEnvironmentPropagatingObject.swift

@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+import Foundation
 import ViewEnvironment
 
 /// A protocol describing a ``ViewEnvironmentPropagating`` object that can: