Allow desired retention to be set to 0.7

https://github.com/open-spaced-repetition/fsrs-rs/issues/79#issuecomment-1733779005

rslib/src/deckconfig/mod.rs

@@ -270,7 +270,7 @@ pub(crate) fn ensure_deck_config_values_valid(config: &mut DeckConfigInner) {
     ensure_f32_valid(
         &mut config.desired_retention,
         default.desired_retention,
-        0.8,
+        0.7,
         0.97,
     );
 }

ts/deck-options/FsrsOptions.svelte

@@ -189,7 +189,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 <SpinBoxFloatRow
     bind:value={$config.desiredRetention}
     defaultValue={defaults.desiredRetention}
-    min={0.8}
+    min={0.7}
     max={0.97}
 >
     <SettingTitle>