Release v5.2.1 (#37098)

* Bump version to v5.2.1.

* Dist

js/dist/scrollspy.js

@@ -1,5 +1,5 @@
 /*!
-  * Bootstrap scrollspy.js v5.2.0 (https://getbootstrap.com/)
+  * Bootstrap scrollspy.js v5.2.1 (https://getbootstrap.com/)
   * Copyright 2011-2022 The Bootstrap Authors (https://github.com/twbs/bootstrap/graphs/contributors)
   * Licensed under MIT (https://github.com/twbs/bootstrap/blob/main/LICENSE)
   */
@@ -17,7 +17,7 @@
 
   /**
    * --------------------------------------------------------------------------
-   * Bootstrap (v5.2.0): scrollspy.js
+   * Bootstrap (v5.2.1): scrollspy.js
    * Licensed under MIT (https://github.com/twbs/bootstrap/blob/main/LICENSE)
    * --------------------------------------------------------------------------
    */
@@ -48,14 +48,16 @@
     // TODO: v6 @deprecated, keep it for backwards compatibility reasons
     rootMargin: '0px 0px -25%',
     smoothScroll: false,
-    target: null
+    target: null,
+    threshold: [0.1, 0.5, 1]
   };
   const DefaultType = {
     offset: '(number|null)',
     // TODO v6 @deprecated, keep it for backwards compatibility reasons
     rootMargin: 'string',
     smoothScroll: 'boolean',
-    target: 'element'
+    target: 'element',
+    threshold: 'array'
   };
   /**
    * Class definition
@@ -116,7 +118,14 @@
 
     _configAfterMerge(config) {
       // TODO: on v6 target should be given explicitly & remove the {target: 'ss-target'} case
-      config.target = index.getElement(config.target) || document.body;
+      config.target = index.getElement(config.target) || document.body; // TODO: v6 Only for backwards compatibility reasons. Use rootMargin only
+
+      config.rootMargin = config.offset ? `${config.offset}px 0px -30%` : config.rootMargin;
+
+      if (typeof config.threshold === 'string') {
+        config.threshold = config.threshold.split(',').map(value => Number.parseFloat(value));
+      }
+
       return config;
     }
 
@@ -152,8 +161,8 @@
     _getNewObserver() {
       const options = {
         root: this._rootElement,
-        threshold: [0.1, 0.5, 1],
-        rootMargin: this._getRootMargin()
+        threshold: this._config.threshold,
+        rootMargin: this._config.rootMargin
       };
       return new IntersectionObserver(entries => this._observerCallback(entries), options);
     } // The logic of selection
@@ -198,11 +207,6 @@
           activate(entry);
         }
       }
-    } // TODO: v6 Only for backwards compatibility reasons. Use rootMargin only
-
-
-    _getRootMargin() {
-      return this._config.offset ? `${this._config.offset}px 0px -30%` : this._config.rootMargin;
     }
 
     _initializeTargetsAndObservables() {