Issue #1201 capture output example tests (#1203)

Fixes #1201

# Description
Print stderr and stdout message when example in ``test_examples.py``
fails.

It will print a message like:

```
    @pytest.mark.parametrize("example", get_examples())
    def test_example(example):
        result = subprocess.run([sys.executable, example], capture_output=True)
        if result.returncode != 0:
>           raise RuntimeError(
                f"Example failed to run with returncode: {result.returncode} \n\n"
                f"stdout: {result.stdout.decode()} \n\n"
                f"stderr: {result.stderr.decode()} \n\n"
            )
E           RuntimeError: Example failed to run with returncode: 1 
E           
E           stdout:  
E           
E           stderr: Unzipping contents of 'C:\Users\Herman\AppData\Local\imod\imod\Cache\hondsrug-simulation.zip' to 'C:\Users\Herman\AppData\Local\Temp\tmpkhwjabqu\hondsrug_saved'
E           Traceback (most recent call last):
E             File "c:\src\imod-python\examples\mf6\hondsrug_partitioning.py", line 52, in <module>
E               raise ValueError("Some failure")
E           ValueError: Some failure
```

# Checklist
- [x] Links to correct issue
- [ ] Update changelog, if changes affect users
- [x] PR title starts with ``Issue #nr``, e.g. ``Issue #737``
- [ ] Unit tests were added
- [ ] **If feature added**: Added/extended example

Author: JoerivanEngelen

imod/tests/test_examples.py

@@ -19,4 +19,10 @@ def get_examples():
 @pytest.mark.example
 @pytest.mark.parametrize("example", get_examples())
 def test_example(example):
-    subprocess.run([sys.executable, example], check=True)
+    result = subprocess.run([sys.executable, example], capture_output=True)
+    if result.returncode != 0:
+        raise RuntimeError(
+            f"Example failed to run with returncode: {result.returncode} \n\n"
+            f"stdout: {result.stdout.decode()} \n\n"
+            f"stderr: {result.stderr.decode()} \n\n"
+        )