puppet: Adjust wal-g release version and SHA256.

wal-g apparently removed the 1.1.1 release; replace it with the
equivalent rc.

puppet/zulip/manifests/postgresql_backups.pp

@@ -3,12 +3,12 @@
 class zulip::postgresql_backups {
   include zulip::postgresql_common
 
-  $wal_g_version = '1.1.1'
+  $wal_g_version = '1.1.1-rc'
   $bin = "/usr/local/bin/wal-g-${wal_g_version}"
   $package = "wal-g-pg-ubuntu-20.04-${::architecture}"
   zulip::sha256_tarball_to { 'wal-g':
     url     => "https://github.com/wal-g/wal-g/releases/download/v${wal_g_version}/${package}.tar.gz",
-    sha256  => '159e66a8e70254783a6a16676f1a663c795950e7e6f526726411a5111a520d1a',
+    sha256  => 'eed4de63c2657add6e0fe70f8c0fbe62a4a54405b9bfc801b1912b6c4f2c7107',
     install => {
       $package => $bin,
     },