fix(lib): Fix string literals in protofile exports

Should only affect python2/jython in burp

lib/blackboxprotobuf/lib/protofile.py

@@ -96,17 +96,17 @@
 
 def _print_message(message_name, typedef, output_file, depth=0):
     # type: (str, TypeDef, TextIO, int) -> None
-    indent = "  " * depth
+    indent = six.u("  ") * depth
     if not NAME_REGEX.match(message_name):
         raise TypedefException("Message name: %s is not valid" % message_name)
 
     # sort typedef for better looking output
     typedef = blackboxprotobuf.lib.api.sort_typedef(typedef)
 
     message_name = message_name.strip()
-    output_file.write("\n")
+    output_file.write(six.u("\n"))
     output_file.write(indent)
-    output_file.write("message %s {\n" % message_name)
+    output_file.write(six.u("message %s {\n") % message_name)
     for field_number, field_typedef in typedef.items():
         proto_type = None
         field_name = None
@@ -155,7 +155,7 @@ def _print_message(message_name, typedef, output_file, depth=0):
 
         output_file.write(indent)
         output_file.write(
-            "  %s%s %s = %s%s;\n"
+            six.u("  %s%s %s = %s%s;\n")
             % (
                 "repeated " if is_repeated else "",
                 proto_type,
@@ -166,7 +166,7 @@ def _print_message(message_name, typedef, output_file, depth=0):
         )
 
     output_file.write(indent)
-    output_file.write("}\n\n")
+    output_file.write(six.u("}\n\n"))
 
 
 def export_proto(typedef_map, output_filename=None, output_file=None, package=None):
@@ -184,9 +184,9 @@ def export_proto(typedef_map, output_filename=None, output_file=None, package=No
         output_file = io.StringIO()
 
     # preamble
-    output_file.write('syntax = "proto3";\n\n')
+    output_file.write(six.u('syntax = "proto3";\n\n'))
     if package:
-        output_file.write("package %s;\n\n" % package)
+        output_file.write(six.u("package %s;\n\n") % package)
 
     for typedef_name, typedef in typedef_map.items():
         _print_message(typedef_name, typedef, output_file)