fix(plpgsql-check): add missing upgrade path files between versions

Generate empty SQL files for version-to-version upgrade paths to satisfy
PostgreSQL extension upgrade requirements.

Author: jfroche

nix/ext/plpgsql-check.nix

@@ -110,6 +110,16 @@ buildEnv {
       ls -la $out/lib/*${postgresql.dlSuffix} || true
       exit 1
     fi
+
+    # Create empty upgrade files between consecutive versions
+    # plpgsql_check ships without upgrade scripts - extensions are backward-compatible
+    previous_version=""
+    for ver in ${lib.concatStringsSep " " versions}; do
+      if [[ -n "$previous_version" ]]; then
+        touch $out/share/postgresql/extension/${pname}--''${previous_version}--''${ver}.sql
+      fi
+      previous_version=$ver
+    done
   '';
 
   passthru = {