Fix jinja2 dump in temporary file for Windows

tempfile.NamedTemporaryFile() creates **and opens** the file.
jinja2.stream().dump() will try to open the file too, if given a str
(filename). This does not cause issue on Linux, but on Windows the same
file cannot be open twice at the same time...

The solution was to pass a file pointer to 'dump()' instead of the
filename, so jinja2 does not need to open it again.

lokrez/export.py

@@ -63,7 +63,7 @@ def generate_outfile(
                                 )
                 import subprocess
 
-                jj2_tpl.stream(context).dump( tmpsvg.name )
+                jj2_tpl.stream(context).dump( tmpsvg )
 
                 inkscape_process = subprocess.Popen(
                         [