fix: keep_download condition

improve condition readability

lib/functions/installs.bash

@@ -237,11 +237,11 @@ install_tool_version() {
       # Remove download directory if --keep-download flag or always_keep_download config setting are not set
       if [ -d "$download_path" ]; then
         always_keep_download=$(get_asdf_config_value "always_keep_download")
-        if [ "$keep_download" != "true" ] && [ "$always_keep_download" != "yes" ]; then
-          rm -r "$download_path"
-        else
+        if [ "$keep_download" = "true" ] || [ "$always_keep_download" = "yes" ]; then
           printf '%s\n' "asdf: Warn: You have configured asdf to preserve downloaded files (with always_keep_download=yes or --keep-download). But" >&2
           printf '%s\n' "asdf: Warn: the current plugin ($plugin_name) does not support that. Downloaded files will not be preserved." >&2
+        else
+          rm -r "$download_path"
         fi
       fi