Fix TypeError "environment can only contain strings"

Apparently Windows Python doesn't coerce pathlib.Path to str.

src/ocrmypdf/api.py

@@ -158,7 +158,7 @@ def create_options(*, input_file, output_file, **kwargs):
 
     # If we are running a Tesseract spoof, ensure it knows what the input file is
     if os.environ.get('PYTEST_CURRENT_TEST') and options.tesseract_env:
-        options.tesseract_env['_OCRMYPDF_TEST_INFILE'] = input_file
+        options.tesseract_env['_OCRMYPDF_TEST_INFILE'] = os.fspath(input_file)
 
     return options
 

tests/conftest.py

@@ -183,7 +183,7 @@ def check_ocrmypdf(input_file, output_file, *args, env=None):
     api.check_options(options)
     if env:
         options.tesseract_env = env
-        options.tesseract_env['_OCRMYPDF_TEST_INFILE'] = input_file
+        options.tesseract_env['_OCRMYPDF_TEST_INFILE'] = os.fspath(input_file)
     result = api.run_pipeline(options, api=True)
 
     assert result == 0