tests: adjust self-copy tests

There are a couple tests which attempt to copy an object onto itself via
a `std::move`.  GCC 13 catches this as a "move onto self" and flags it
as an error.  Rather than use the `std::move`, perform a static_cast
into an r-value reference so that the same copy-constructor is called
as if the std::move were successfully used.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I097889578492b1a3ab456e8cb21a668aa0855be4
diff --git a/test/file_descriptor_tests.cpp b/test/file_descriptor_tests.cpp
index 4273086..ad63dd7 100644
--- a/test/file_descriptor_tests.cpp
+++ b/test/file_descriptor_tests.cpp
@@ -131,7 +131,7 @@
         EXPECT_TRUE(isValid(fd));
 
         // Try to move object into itself
-        descriptor = std::move(descriptor);
+        descriptor = static_cast<FileDescriptor&&>(descriptor);
 
         // Verify object still contains file descriptor
         EXPECT_EQ(descriptor(), fd);