Update release date.

CHANGES.md

@@ -2,7 +2,7 @@ Changes in PDFio
 ================
 
 
-v1.5.2 - YYYY-MM-DD
+v1.5.2 - 2025-04-12
 -------------------
 
 - Updated maximum allowed PDF string size to 64k (Issue #117)

makesrcdist

@@ -32,11 +32,11 @@ if test $(grep AC_INIT configure.ac | awk '{print $2}') != "[$version],"; then
     status=1
 fi
 
-if test $(head -4 CHANGES.md | tail -1 | awk '{print $1}') != "v$version"; then
+if test $(head -5 CHANGES.md | tail -1 | awk '{print $1}') != "v$version"; then
     echo "Still need to update CHANGES.md version number."
     status=1
 fi
-if test $(head -4 CHANGES.md | tail -1 | awk '{print $3}') = "YYYY-MM-DD"; then
+if test $(head -5 CHANGES.md | tail -1 | awk '{print $3}') = "YYYY-MM-DD"; then
     echo "Still need to update CHANGES.md release date."
     status=1
 fi