Prepare new upstream release 0.5.0

debian/changelog

+pgvector (0.5.0-1) UNRELEASED; urgency=medium
+
+  * Upstream Release 0.5.0
+    - Features:
+      * Added HNSW index type
+      * Added support for parallel index builds for IVFFlat
+      * Added l1_distance function
+      * Added element-wise multiplication for vectors
+      * Added sum aggregate
+    - Improvements:
+      * Improved performance of distance functions
+    - Fixes:
+      * Fixed out of range results for cosine distance
+      * Fixed results for NULL and NaN distances for IVFFlat
+
+ -- Bradford D. Boyle <bradford.d.boyle@gmail.com>  Thu, 31 Aug 2023 04:57:11 +0000
+
 pgvector (0.4.4-1) unstable; urgency=medium
 
   * Upstream Release 0.4.3