nsis: Use solid lzma compressor

File sizes, 32 bit:
- default: 64 MB
- lzma: 50 MB
- lzma solid: 47 MB

64 bit:
- default: 75 MB
- lzma: 58 MB
- lzma solid: 55 MB

Between lzma and lzma solid, installation speed doesn't seem to vary much, so
let's go for the smallest.

misc/qutebrowser.nsi

@@ -2,6 +2,7 @@ Name "qutebrowser"
 
 Unicode true
 RequestExecutionLevel admin
+SetCompressor /solid lzma
 
 !ifdef X64
   OutFile "..\dist\qutebrowser-${VERSION}-amd64.exe"