Get XMP metadata from image using Pillow. Remove ExifTool dependency

- Pillow already supports reading XMP metadata from Images
- Removes need to maintain my fork of unmaintained PyExiftool
  - This also removes dependency on system Exiftool package for
    XMP metadata extraction
- Add test to verify XMP metadata extracted from test images
- Remove references to Exiftool from Documentation

tests/test_image_search.py

@@ -25,6 +25,28 @@ def test_image_search_setup(content_config: ContentConfig, search_config: Search
     assert len(image_search_model.image_embeddings) == 3
 
 
+def test_image_metadata(content_config: ContentConfig):
+    "Verify XMP Description and Subjects Extracted from Image"
+    # Arrange
+    expected_metadata_image_name_pairs = [
+        (["Billi Ka Bacha.", "Cat", "Grass"], "kitten_park.jpg"),
+        (["Pasture.", "Horse", "Dog"], "horse_dog.jpg"),
+        (["Guinea Pig Eating Celery.", "Rodent", "Whiskers"], "guineapig_grass.jpg")]
+
+    test_image_paths = [
+        Path(content_config.image.input_directories[0] / image_name[1])
+        for image_name in expected_metadata_image_name_pairs
+    ]
+
+    for expected_metadata, test_image_path in zip(expected_metadata_image_name_pairs, test_image_paths):
+        # Act
+        actual_metadata = image_search.extract_metadata(test_image_path)
+
+        # Assert
+        for expected_snippet in expected_metadata[0]:
+            assert expected_snippet in actual_metadata
+
+
 # ----------------------------------------------------------------------------------------------------
 def test_image_search(content_config: ContentConfig, search_config: SearchConfig):
     # Arrange