fix python sat boolean value method in solution callback.
fix python sat boolean value method in solution callback.

or-tools/or-tools,google/or-tools,google/or-tools,google/or-tools,or-tools/or-tools,google/or-tools,or-tools/or-tools,or-tools/or-tools,google/or-tools,or-tools/or-tools,or-tools/or-tools,google/or-tools