Upgrade to ebookmaker 0.11.28

0.11.28 has a bug fix to allow the use of the `--output-file` argument to set
the output filename correctly.

Author: windymilla

Pipfile

@@ -8,7 +8,7 @@ verify_ssl = true
 [packages]
 pywin32-ctypes = "*"
 pyinstaller = "==4.7"
-ebookmaker = "==0.11.26"
+ebookmaker = "==0.11.28"
 
 [requires]
 python_version = "3.8"