fix: use UTF-8 encoding when opening files (#704)

### Summary of Changes

Explictly use UTF-8 encoding when opening files. This fixes errors when
opening a CSV or JSON file like

```
UnicodeDecodeError: 'charmap' codec can't decode byte 0x9d in position 6: character maps to <undefined>
```

if they contained non-ASCII tokens.

src/safeds/data/tabular/containers/_table.py

@@ -109,7 +109,7 @@ def from_csv_file(path: str | Path) -> Table:
         if path.suffix != ".csv":
             raise WrongFileExtensionError(path, ".csv")
         if path.exists():
-            with path.open() as f:
+            with path.open(encoding="utf-8") as f:
                 if f.read().replace("\n", "") == "":
                     return Table()
 
@@ -200,7 +200,7 @@ def from_json_file(path: str | Path) -> Table:
         if path.suffix != ".json":
             raise WrongFileExtensionError(path, ".json")
         if path.exists():
-            with path.open() as f:
+            with path.open(encoding="utf-8") as f:
                 if f.read().replace("\n", "") in ("", "{}"):
                     return Table()
 

tests/resources/table.csv

@@ -1,2 +1,2 @@
 A,B
-1,2
+❔,2

tests/resources/table.json

@@ -1,6 +1,6 @@
 [
     {
-        "A": 1,
+        "A": "❔",
         "B": 2
     }
 ]

tests/safeds/data/tabular/containers/_table/test_from_csv_file.py

@@ -10,8 +10,8 @@
 @pytest.mark.parametrize(
     ("path", "expected"),
     [
-        ("table.csv", Table({"A": [1], "B": [2]})),
-        (Path("table.csv"), Table({"A": [1], "B": [2]})),
+        ("table.csv", Table({"A": ["❔"], "B": [2]})),
+        (Path("table.csv"), Table({"A": ["❔"], "B": [2]})),
         ("emptytable.csv", Table()),
     ],
     ids=["by String", "by path", "empty"],

tests/safeds/data/tabular/containers/_table/test_from_json_file.py

@@ -10,8 +10,8 @@
 @pytest.mark.parametrize(
     ("path", "expected"),
     [
-        ("table.json", Table({"A": [1], "B": [2]})),
-        (Path("table.json"), Table({"A": [1], "B": [2]})),
+        ("table.json", Table({"A": ["❔"], "B": [2]})),
+        (Path("table.json"), Table({"A": ["❔"], "B": [2]})),
         (Path("emptytable.json"), Table()),
     ],
     ids=["by string", "by path", "empty"],

tests/safeds/data/tabular/containers/_time_series/test_timeseries_from_csv_file.py

@@ -12,9 +12,9 @@
     [
         (
             "table.csv",
-            TimeSeries({"A": [1], "B": [2]}, time_name="A", target_name="B"),
+            TimeSeries({"A": ["❔"], "B": [2]}, time_name="A", target_name="B"),
         ),
-        (Path("table.csv"), TimeSeries({"A": [1], "B": [2]}, time_name="A", target_name="B")),
+        (Path("table.csv"), TimeSeries({"A": ["❔"], "B": [2]}, time_name="A", target_name="B")),
     ],
     ids=["by String", "by path"],
 )