postgresql{12,13}Packages.pg_safeupdate: 1.5 -> 1.4

pg_safeupdate was updated to 1.5 in NixOS#269755. v1.5 is not compatible with
PostgreSQL 12 and 13 anymore, so those were marked as broken.

However, this blocks anyone using PostgreSQL 12 or 13 with pg_safeupdate
from updating nixpkgs.

Instead, the old version should have been kept for PG 12 and 13.

pkgs/servers/sql/postgresql/ext/pg_safeupdate.nix

@@ -1,16 +1,39 @@
 { lib, stdenv, fetchFromGitHub, postgresql }:
 
+with {
+  "12" = {
+    version = "1.4";
+    sha256 = "sha256-1cyvVEC9MQGMr7Tg6EUbsVBrMc8ahdFS3+CmDkmAq4Y=";
+  };
+  "13" = {
+    version = "1.4";
+    sha256 = "sha256-1cyvVEC9MQGMr7Tg6EUbsVBrMc8ahdFS3+CmDkmAq4Y=";
+  };
+  "14" = {
+    version = "1.5";
+    sha256 = "sha256-RRSpkWLFuif+6RCncnsb1NnjKnIIRY9KgebKkjCN5cs=";
+  };
+  "15" = {
+    version = "1.5";
+    sha256 = "sha256-RRSpkWLFuif+6RCncnsb1NnjKnIIRY9KgebKkjCN5cs=";
+  };
+  "16" = {
+    version = "1.5";
+    sha256 = "sha256-RRSpkWLFuif+6RCncnsb1NnjKnIIRY9KgebKkjCN5cs=";
+  };
+}."${lib.versions.major postgresql.version}" or (throw "pg_safeupdate: version specification for pg ${postgresql.version} missing.");
+
 stdenv.mkDerivation rec {
   pname = "pg-safeupdate";
-  version = "1.5";
+  inherit version;
 
   buildInputs = [ postgresql ];
 
   src = fetchFromGitHub {
     owner  = "eradman";
     repo   = pname;
     rev    = version;
-    sha256 = "sha256-RRSpkWLFuif+6RCncnsb1NnjKnIIRY9KgebKkjCN5cs=";
+    inherit sha256;
   };
 
   installPhase = ''
@@ -24,6 +47,5 @@ stdenv.mkDerivation rec {
     platforms   = postgresql.meta.platforms;
     maintainers = with maintainers; [ wolfgangwalther ];
     license     = licenses.postgresql;
-    broken      = versionOlder postgresql.version "14";
   };
 }