Update COPYRIGHT file

Author: Manishearth

COPYRIGHT

@@ -339,3 +339,53 @@ their own copyright notices and license terms:
     NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
     USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
     OF SUCH DAMAGE.
+
+* Portions of internationalization code use code or data from Unicode, which
+  carry the following license:
+
+      UNICODE, INC. LICENSE AGREEMENT - DATA FILES AND SOFTWARE
+
+    See Terms of Use <https://www.unicode.org/copyright.html>
+    for definitions of Unicode Inc.’s Data Files and Software.
+
+    NOTICE TO USER: Carefully read the following legal agreement.
+    BY DOWNLOADING, INSTALLING, COPYING OR OTHERWISE USING UNICODE INC.'S
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+    TERMS AND CONDITIONS OF THIS AGREEMENT.
+    IF YOU DO NOT AGREE, DO NOT DOWNLOAD, INSTALL, COPY, DISTRIBUTE OR USE
+    THE DATA FILES OR SOFTWARE.
+
+    COPYRIGHT AND PERMISSION NOTICE
+
+    Copyright © 1991-2022 Unicode, Inc. All rights reserved.
+    Distributed under the Terms of Use in https://www.unicode.org/copyright.html.
+
+    Permission is hereby granted, free of charge, to any person obtaining
+    a copy of the Unicode data files and any associated documentation
+    (the "Data Files") or Unicode software and any associated documentation
+    (the "Software") to deal in the Data Files or Software
+    without restriction, including without limitation the rights to use,
+    copy, modify, merge, publish, distribute, and/or sell copies of
+    the Data Files or Software, and to permit persons to whom the Data Files
+    or Software are furnished to do so, provided that either
+    (a) this copyright and permission notice appear with all copies
+    of the Data Files or Software, or
+    (b) this copyright and permission notice appear in associated
+    Documentation.
+
+    THE DATA FILES AND SOFTWARE ARE PROVIDED "AS IS", WITHOUT WARRANTY OF
+    ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
+    WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+    NONINFRINGEMENT OF THIRD PARTY RIGHTS.
+    IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS
+    NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL
+    DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+    DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+    TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+    PERFORMANCE OF THE DATA FILES OR SOFTWARE.
+
+    Except as contained in this notice, the name of a copyright holder
+    shall not be used in advertising or otherwise to promote the sale,
+    use or other dealings in these Data Files or Software without prior
+    written authorization of the copyright holder.