Change type of the error message to String

Since this is for testing it doesn't need to be optimised unnecessarily

substrate/frame/support/src/storage/storage_noop_guard.rs

@@ -39,14 +39,14 @@
 #[must_use]
 pub struct StorageNoopGuard {
 	storage_root: sp_std::vec::Vec<u8>,
-	error_message: &'static str,
+	error_message: String,
 }
 
 impl Default for StorageNoopGuard {
 	fn default() -> Self {
 		Self {
 			storage_root: sp_io::storage::root(sp_runtime::StateVersion::V1),
-			error_message: "`StorageNoopGuard` detected an attempted storage change.",
+			error_message: String::from("`StorageNoopGuard` detected an attempted storage change."),
 		}
 	}
 }
@@ -58,12 +58,12 @@ impl StorageNoopGuard {
 	}
 
 	/// Creates a new [`StorageNoopGuard`] with a custom error message.
-	pub fn from_error_message(error_message: &'static str) -> Self {
+	pub fn from_error_message(error_message: String) -> Self {
 		Self { storage_root: sp_io::storage::root(sp_runtime::StateVersion::V1), error_message }
 	}
 
 	/// Sets a custom error message for a [`StorageNoopGuard`].
-	pub fn set_error_message(&mut self, error_message: &'static str) {
+	pub fn set_error_message(&mut self, error_message: String) {
 		self.error_message = error_message;
 	}
 }
@@ -140,9 +140,9 @@ mod tests {
 	#[should_panic(expected = "`StorageNoopGuard` found unexpected storage changes.")]
 	fn storage_noop_guard_panics_created_from_error_message() {
 		TestExternalities::default().execute_with(|| {
-			let _guard = StorageNoopGuard::from_error_message(
+			let _guard = StorageNoopGuard::from_error_message(String::from(
 				"`StorageNoopGuard` found unexpected storage changes.",
-			);
+			));
 			frame_support::storage::unhashed::put(b"key", b"value");
 		});
 	}
@@ -152,7 +152,9 @@ mod tests {
 	fn storage_noop_guard_panics_with_set_error_message() {
 		TestExternalities::default().execute_with(|| {
 			let mut guard = StorageNoopGuard::default();
-			guard.set_error_message("`StorageNoopGuard` found unexpected storage changes.");
+			guard.set_error_message(String::from(
+				"`StorageNoopGuard` found unexpected storage changes.",
+			));
 			frame_support::storage::unhashed::put(b"key", b"value");
 		});
 	}