Update pyapp.nsi

I went with `0x02ffffff` since Anders mentioned it being the "official way", but I agree that `0x03000000` is better – it's more readable IMHO. I've also added `ManifestDPIAware`. Please let me know if I should undo the whitespace changes, they weren't intentional.

nsist/pyapp.nsi

@@ -12,8 +12,9 @@
 
 SetCompressor lzma
 
-!if "${NSIS_PACKEDVERSION}" > 0x02ffffff
+!if "${NSIS_PACKEDVERSION}" >= 0x03000000
   Unicode true
+  ManifestDPIAware true
 !endif
 
 !define MULTIUSER_EXECUTIONLEVEL Highest