Add test of common PartialEq cases

tests/test_partialeq.rs

@@ -0,0 +1,13 @@
+use serde_bytes::{Bytes, ByteBuf};
+
+fn _bytes_eq_slice(bytes: &Bytes, slice: &[u8]) -> bool {
+    bytes == slice
+}
+
+fn _bytebuf_eq_vec(bytebuf: ByteBuf, vec: Vec<u8>) -> bool {
+    bytebuf == vec
+}
+
+fn _bytes_eq_bytestring(bytes: &Bytes) -> bool {
+    bytes == b"..."
+}