workflow.py graph save does not handle paths with dots in them correctly

[jpfleischer]

    if engine == "dot":
            prefix, ending = filename.split(".")
            dot_filename = prefix + ".dot"
            writefile(dot_filename, str(dot.source))
            os.system(f"dot -T{ending} {dot_filename} -o {filename}")

this fails when filename is something like ~/.cloudmesh/workflow/workflow/workflow.svg

[jpfleischer]

we easily fix by using

      basefilename = os.path.basename(filename)
      prefix, ending = basefilename.split(".")

fix will be pushed soon

[jpfleischer]

fixed 9ad6d45