post rustfmt whitespace fixup (#9436)

Taking best bits of rustfmt's format_strings

Co-authored-by: Alexander Popiak <alexander.popiak@gmail.com>

substrate/bin/node/runtime/src/lib.rs

@@ -101,9 +101,9 @@ include!(concat!(env!("OUT_DIR"), "/wasm_binary.rs"));
 #[cfg(feature = "std")]
 pub fn wasm_binary_unwrap() -> &'static [u8] {
 	WASM_BINARY.expect(
-		"Development wasm binary is not available. This means the client is \
-						built with `SKIP_WASM_BUILD` flag and it is only usable for \
-						production chains. Please rebuild with the flag disabled.",
+		"Development wasm binary is not available. This means the client is built with \
+		 `SKIP_WASM_BUILD` flag and it is only usable for production chains. Please rebuild with \
+		 the flag disabled.",
 	)
 }