Don't warn about .sh.version being unused (for Ksh)

ShellCheck/Analytics.hs

@@ -1834,6 +1834,7 @@ prop_checkUnassignedReferences24= verifyNotTree checkUnassignedReferences "decla
 prop_checkUnassignedReferences25= verifyNotTree checkUnassignedReferences "declare -A foo=(); foo[bar]=42;"
 prop_checkUnassignedReferences26= verifyNotTree checkUnassignedReferences "a::b() { foo; }; readonly -f a::b"
 prop_checkUnassignedReferences27= verifyNotTree checkUnassignedReferences ": ${foo:=bar}"
+prop_checkUnassignedReferences28= verifyNotTree checkUnassignedReferences "#!/bin/ksh\necho \"${.sh.version}\"\n"
 checkUnassignedReferences params t = warnings
   where
     (readMap, writeMap) = execState (mapM tally $ variableFlow params) (Map.empty, Map.empty)

ShellCheck/Data.hs

@@ -33,6 +33,9 @@ internalVariables = [
     -- Other
     "USER", "TZ", "TERM", "LOGNAME", "LD_LIBRARY_PATH", "LANGUAGE", "DISPLAY",
     "HOSTNAME", "KRB5CCNAME", "XAUTHORITY"
+
+    -- Ksh
+    , ".sh.version"
   ]
 
 variablesWithoutSpaces = [