dovecot_pigeonhole: 0.5.5 -> 0.5.6

Semi-automatic update generated by
https://github.com/ryantm/nixpkgs-update tools. This update was made
based on information from
https://repology.org/metapackage/dovecot-pigeonhole/versions

pkgs/servers/mail/dovecot/plugins/pigeonhole/default.nix

@@ -2,11 +2,11 @@
 
 stdenv.mkDerivation rec {
   name = "dovecot-pigeonhole-${version}";
-  version = "0.5.5";
+  version = "0.5.6";
 
   src = fetchurl {
     url = "https://pigeonhole.dovecot.org/releases/2.3/dovecot-2.3-pigeonhole-${version}.tar.gz";
-    sha256 = "19a9a6rdvdlrm00k2npprj6lrikjhngnmpgg412848rb3ip11anb";
+    sha256 = "1f7m2213w4hvqr3lvr03bv4lh92k35gxl01c2x8q8akk7viffbvw";
   };
 
   buildInputs = [ dovecot openssl ];