$ pacman -S mingw-w64-i686-python3-gobject mingw-w64-i686-python3-cairo
warning: mingw-w64-i686-python3-gobject-3.22.0-1 is up to date -- reinstalling
warning: mingw-w64-i686-python3-cairo-1.10.0-6 is up to date -- reinstalling
resolving dependencies...
looking for conflicting packages...

Packages (2) mingw-w64-i686-python3-cairo-1.10.0-6
             mingw-w64-i686-python3-gobject-3.22.0-1

Total Installed Size:  0.73 MiB
Net Upgrade Size:      0.00 MiB

:: Proceed with installation? [Y/n] y
(2/2) checking keys in keyring                     [#####################] 100%
(2/2) checking package integrity                   [#####################] 100%
(2/2) loading package files                        [#####################] 100%
(2/2) checking for file conflicts                  [#####################] 100%
(2/2) checking available disk space                [#####################] 100%
:: Processing package changes...
(1/2) reinstalling mingw-w64-i686-python3-cairo    [#####################] 100%
(2/2) reinstalling mingw-w64-i686-python3-gobject  [#####################] 100%

$ python3 app.py
Traceback (most recent call last):
  File "app.py", line 7, in <module>
    import cairo
  File "C:/msys64/mingw32/lib/python3.5/site-packages\cairo\__init__.py", line 18, in <module>
    from ._cairo import *
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xec in position 5: invalid continuation byte