Specify UTF-8 encoding when opening files

Added explicit encoding="utf-8" to file open calls in omex.py and test_legacy.py to ensure consistent file reading across different environments.

Author: JR-1991

pyenzyme/sbml/omex.py

@@ -184,4 +184,7 @@ def read_sbml_omex(path: Path | str) -> tuple[TextIO, dict[str, pd.DataFrame]]:
 
         meas_data[entry.location] = df
 
-    return open(omex.get_path(master_file.location)), meas_data
+    return open(
+        omex.get_path(master_file.location),
+        encoding="utf-8",
+    ), meas_data

tests/integration/test_legacy.py

@@ -16,7 +16,7 @@ def test_legacy(self):
         consistent and expected output for legacy OMEX files.
         """
         enzmldoc = EnzymeMLDocument.fromFile("tests/fixtures/sbml/v1_example.omex")
-        expected = open("tests/fixtures/sbml/v1_sbml.xml", "r").read()
+        expected = open("tests/fixtures/sbml/v1_sbml.xml", "r", encoding="utf-8").read()
         actual = enzmldoc.toXMLString()
 
         assert actual == expected