Add copyright notice and licensing information to slugify function

Author: ahosgood

tna_utilities/string.py

@@ -8,6 +8,34 @@ def slugify(value: str, allow_unicode=False) -> str:
 
     Derived from Django
     https://github.com/django/django/blob/stable/6.0.x/django/utils/text.py#L469-L486
+
+    Copyright (c) Django Software Foundation and individual contributors.
+    All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without modification,
+    are permitted provided that the following conditions are met:
+
+        1. Redistributions of source code must retain the above copyright notice,
+        this list of conditions and the following disclaimer.
+
+        2. Redistributions in binary form must reproduce the above copyright
+        notice, this list of conditions and the following disclaimer in the
+        documentation and/or other materials provided with the distribution.
+
+        3. Neither the name of Django nor the names of its contributors may be used
+        to endorse or promote products derived from this software without
+        specific prior written permission.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+    ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+    DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+    ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+    (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+    ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     """
 
     if not isinstance(value, str):