v3.31.1: the Linux PC/SC headers (pyscard builds from source)

The first release run failed installing the test dependencies:
pyscard 2.3.1 publishes macOS and Windows wheels only (no manylinux),
so on Linux it always builds from source and needs the PC/SC headers -
the job stopped at "winscard.h: No such file or directory".

- The release workflow installs libpcsclite-dev before the dependencies.
- The READMEs and setup.sh name the header package next to pcscd/ccid:
  libpcsclite-dev (Debian/Ubuntu), pcsc-lite-devel (Fedora), included
  in Arch's pcsclite.  This affects every Linux user running setup, not
  just CI.
- Version strings + the PWA cache bumped together (simple-v456).

No runtime change: 997 Python + 953 frontend green; the release package
test builds with the new version.

frontend/index.html

@@ -1943,7 +1943,7 @@
 // ===== Version =====
 // Single source of truth for the PWA version: shown in the header and used
 // by the server version check in pysimConnect().
-const SIMPLE_VERSION = '3.31.0';
+const SIMPLE_VERSION = '3.31.1';
 document.getElementById('app-version').textContent = 'v' + SIMPLE_VERSION;
 
 // ===== view history (the browser Back/Forward buttons) =====

frontend/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'simple-v455';
+const CACHE = 'simple-v456';
 const URLS = [
   'index.html',
   'help.html',