ifed out embedded and swift 6 only test case

Author: sliemeobn

Sources/Elementary/ServerSupport/SendOnceBox.swift

@@ -1,4 +1,4 @@
-#if swift(>=6.0)
+#if swift(>=6.0) && !hasFeature(Embedded)
 import Synchronization
 
 @available(macOS 15.0, *)

Sources/Elementary/ServerSupport/SendableAnyHTMLBox.swift

@@ -1,3 +1,4 @@
+#if !hasFeature(Embedded)
 /// A wrapper around an `any HTML` value that can be safely sent once.
 ///
 /// Note: For non-sendable values, this will only allow the value to be taken only once.
@@ -42,3 +43,4 @@ public struct _SendableAnyHTMLBox: Sendable {
     }
     #endif
 }
+#endif

Tests/ElementaryTests/SendableAnyHTMLBox.swift

@@ -10,12 +10,14 @@ final class SendOnceHTMLValueTests: XCTestCase {
         XCTAssertNotNil(box.tryTake())
     }
 
+    #if swift(>=6.0)
     func testHoldsNonSendable() {
         let html = MyComponent()
         let box = _SendableAnyHTMLBox(html)
         XCTAssertNotNil(box.tryTake())
         XCTAssertNil(box.tryTake())
     }
+    #endif
 }
 
 class NonSendable {