Switch from apply filter run to let filter run

core/wiki/macros/CSS.tid

@@ -150,7 +150,7 @@ tags: $:/tags/Macro
 \end tf.check-colour-contrast
 
 \function tf.interpolate-colours(paletteEntryA,paletteEntryB,weight)
-[function[colour],<paletteEntryA>] [function[colour],<paletteEntryB>] :apply[<weight>colour-interpolate:oklch<$1>,<$2>]
+[function[colour],<paletteEntryA>] =>colourA [function[colour],<paletteEntryB>] =>colourB [<weight>colour-interpolate:oklch<colourA>,<colourB>]
 \end tf.interpolate-colours
 
 \procedure datauri(title)

editions/test/tiddlers/tests/data/filters/FilterRunPrefixesApply.tid

@@ -1,13 +0,0 @@
-title: Filters/FilterRunPrefixes/Applu
-description: Applu filter run prefix
-type: text/vnd.tiddlywiki-multiple
-tags: [[$:/tags/wiki-test-spec]]
-
-title: Output
-
-\whitespace trim
-<$text text={{{ a b c :apply[<$1>addsuffix<$2>addsuffix<$3>] }}}/>
-+
-title: ExpectedResult
-
-<p>abc</p>

editions/tw5.com/tiddlers/releasenotes/5.4.0/#8702.tid

@@ -24,4 +24,3 @@ To make all of these new features possible, this PR also includes some useful ne
 * Several new filter operators for manipulating colour values. The underlying functionality comes from the [[color.js|https://colorjs.io/]] library
 * New media query tracking mechanism that can track the results of any CSS media query (not just dark mode), storing the results in a shadow `$:/info/...` tiddler
 * New `changecount` filter operator
-* New `:apply` filter run prefix (to be replaced by the `:let` filter run prefix in [[#8972|https://github.com/TiddlyWiki/TiddlyWiki5/pull/8972]]))