Use subprocess to handle spaces in executable path

[isidroas]

Closes #359

I also noticed that the sys.executable is not necessary in my case:

--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -1657,7 +1657,7 @@ def browse():
         def retest(self, pattern):
             with self.suspend():
                 assert sys.argv[-1] == 'browse'
-                subprocess.run([sys.executable, *sys.argv[:-1], 'run', pattern])
+                subprocess.run([*sys.argv[:-1], 'run', pattern])
                 input('press enter to return to browser')

             self.read_data()

But I haven't removed it because I am not sure.