partition_table: Add Python 2 & 3 support

components/partition_table/gen_esp32part.py

@@ -21,6 +21,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 from __future__ import print_function, division
+from __future__ import unicode_literals
 import argparse
 import os
 import re