Fix default values being loaded with wrong encoding on Windows (#1414)

Explicitly set the encoding to utf-8 when reading the context file to
ensure values are correctly loaded.

Co-authored-by: Andrey Shpak <insspb@users.noreply.github.com>

cookiecutter/generate.py

@@ -82,7 +82,7 @@ def generate_context(
     context = OrderedDict([])
 
     try:
-        with open(context_file) as file_handle:
+        with open(context_file, encoding='utf-8') as file_handle:
             obj = json.load(file_handle, object_pairs_hook=OrderedDict)
     except ValueError as e:
         # JSON decoding error.  Let's throw a new exception that is more

tests/test-generate-context/non_ascii.json

@@ -0,0 +1,3 @@
+{
+    "full_name": "éèà"
+}

tests/test_generate_context.py

@@ -108,6 +108,17 @@ def test_default_context_replacement_in_generate_context():
     assert generated_context == expected_context
 
 
+def test_generate_context_decodes_non_ascii_chars():
+    """Verify `generate_context` correctly decodes non-ascii chars."""
+    expected_context = {'non_ascii': OrderedDict([('full_name', 'éèà'),])}
+
+    generated_context = generate.generate_context(
+        context_file='tests/test-generate-context/non_ascii.json'
+    )
+
+    assert generated_context == expected_context
+
+
 @pytest.fixture
 def template_context():
     """Fixture. Populates template content for future tests."""