Add missing upgrade script

And tweak the upgrade incompatibility docs and query.

Author: theory

Changes

@@ -13,9 +13,10 @@ Revision history for PostgreSQL extension semver.
         Fixed a bug in the scanning of pre-releases that start with a zero.
         It now properly scans the rest of the pre-release string. As a result,
         existing semvers with pre-releases the start with a zero may have been
-        incorrectly interpreted as valid. See the v0.30.0 changes below for
-        instructions for finding such invalid semvers. Discovered while
-        debugging unexpected test failures in #70.
+        incorrectly interpreted as valid. Any versions returned by this query
+        will need the leading 0 removed from the pre-release before upgrading:
+        `SELECT version FROM pkg WHERE get_semver_prerelease(version) ~ '^0\[0-9]+($|\+)'`
+        Discovered while debugging unexpected test failures in #70.
 
 0.32.1  2023-08-01T23:20:31Z
       - Fixed compilation issue on Postgres 16.

doc/semver.mmd

@@ -73,6 +73,20 @@ comparison operators, are:
 -------------------------------------------
 
 Prior to v0.40.0, the semver extension incorrectly allowed some invalid
+prerelease values. *BEFORE YOU UPGRADE*, we strongly recommend that you check
+for and repair semvers. Use this query to find semvers with invalid
+pre-release values:
+
+    SELECT name, version FROM packages
+     WHERE get_semver_prerelease(version) ~ '^0\[0-9]+($|\+)';
+
+For any results returned, update them by removing the leading `0` from the
+pre-release, or appending an alphbetic value.
+
+🚨 v0.30.0 Upgrade Compatibility Warning 🚨
+-------------------------------------------
+
+Prior to v0.30.0, the semver extension incorrectly allowed some invalid
 prerelease and build metadata values. Details below, but *BEFORE YOU UPGRADE*
 from an earlier version, we strongly recommend that you check for and repair
 any invalid semvers. You can find them using the official [SemVer regular

sql/semver--0.32.0--0.40.0.sql renamed to sql/semver--0.32.0--0.32.1.sql

@@ -0,0 +1 @@
+-- C source code changes only; No SQL changes.