Update README, snap version, and tag

Author: github-actions[bot]

README.md

@@ -458,7 +458,7 @@ also often get polled from the printer.
   - ghostscript ghostpdl-10.05.0-test-base-001
   - cups v2.4.11
   - libcupsfilters 2.1.1
-  - libppd 2.1.0
+  - libppd 2.1.1
   - cups-filters 2.0.1
   - pyppd release-1-1-0
   - foomatic-db 20240504

rockcraft.yaml

@@ -1,6 +1,6 @@
 name: ghostscript-printer-app
 base: ubuntu@22.04
-version: '10.05.0-8'
+version: '10.05.0-9'
 summary: Ghostscript Printer Application
 description: |
   The Ghostscript Printer Application is a PAPPL (Printer Application
@@ -406,7 +406,7 @@ parts:
   libppd:
     source: https://github.com/OpenPrinting/libppd
     source-type: git
-    source-tag: '2.1.0'
+    source-tag: '2.1.1'
     source-depth: 1
 # ext:updatesnap
 #   version-format: