Log and ignore when meet unknown encoding file

[JaySon-Huang]

First of all, thanks for this fantastic script!

When using this script to handle my codes, the script exit with an exception. I think it is better to log an error and continue for other files in the directory.

I've tested it as follows

>  python3 licenseheaders.py -t templates/apache-2.tmpl -y 2023 -o 'JaySon' -d tests -vv
licenseheaders_0.8.8 INFO: Using file /Users/jayson/Projects/licenseheaders/templates/apache-2.tmpl
licenseheaders_0.8.8 INFO: Processing file tests/driver.py as python
licenseheaders_0.8.8 INFO: Processing file tests/expected/test.h as c
licenseheaders_0.8.8 INFO: Processing file tests/expected/test.cpp as cpp
licenseheaders_0.8.8 INFO: Processing file tests/expected/test.sh as script
licenseheaders_0.8.8 INFO: Processing file tests/expected/test.py as python
licenseheaders_0.8.8 INFO: Processing file tests/expected/CMakeLists.txt as cmake
licenseheaders_0.8.8 INFO: Processing file tests/expected/test.v as ocaml
licenseheaders_0.8.8 ERROR: Exceptions when reading file tests/input/shark0.cc, error='utf-8' codec can't decode byte 0xff in position 0: invalid start byte
licenseheaders_0.8.8 INFO: Processing file tests/input/test.h as c
licenseheaders_0.8.8 INFO: Processing file tests/input/test.cpp as cpp
licenseheaders_0.8.8 INFO: Processing file tests/input/test.sh as script
licenseheaders_0.8.8 INFO: Processing file tests/input/test.py as python
licenseheaders_0.8.8 INFO: Processing file tests/input/CMakeLists.txt as cmake
licenseheaders_0.8.8 INFO: Processing file tests/input/test.v as ocaml