Replace Unicode apostrophe with ASCII apostrophe

In commit babb399, I accidentally introduced a Unicode
apostrophe (U+2019). This commit replaces it with the ASCII
apostrophe (U+0027) for consistency.

Reported-by: Alexander Korotkov <aekorotkov@gmail.com>
Discussion: https://postgr.es/m/CAPpHfduNWMBjkJFtqXJremk6b6YQYO2s3_VEpnj-T_CaUNUYYQ@mail.gmail.com

Author: amitlan

src/backend/commands/tablecmds.c

@@ -18691,7 +18691,7 @@ ATExecAttachPartition(List **wqueue, Relation rel, PartitionCmd *cmd,
 
 	/*
 	 * Use list_concat_copy() to avoid modifying partBoundConstraint in place,
-	 * since it’s needed later to construct the constraint expression for
+	 * since it's needed later to construct the constraint expression for
 	 * validating against the default partition, if any.
 	 */
 	partConstraint = list_concat_copy(partBoundConstraint,