added .wav file workarounds

app/src/main/java/eu/faircode/email/EntityAttachment.java

@@ -231,7 +231,8 @@ public class EntityAttachment {
         if ("audio/mid".equals(type))
             return "audio/midi";
 
-        if ("audio-x/wav".equals(type))
+        if ("audio/x-wav".equals(type) ||
+                "audio-x/wav".equals(type))
             return "audio/wav";
 
         // https://www.rfc-editor.org/rfc/rfc3555.txt
@@ -321,6 +322,9 @@ public class EntityAttachment {
         if ("ogg".equals(extension))
             return "application/ogg";
 
+        if ("wav".equals(extension))
+            return "audio/wav";
+
         // Images
 
         if ("avif".equals(extension))