Update dependency com.vladsch.flexmark:flexmark-all to v0.64.8 (#1909)

Author: nedtwigg

lib/build.gradle

@@ -88,7 +88,7 @@ dependencies {
 	// diktat latest supported version 2.x
 	compatDiktat2Dot0Dot0CompileOnly "com.saveourtool.diktat:diktat-runner:2.0.0"
 	// flexmark
-	flexmarkCompileOnly 'com.vladsch.flexmark:flexmark-all:0.64.0'
+	flexmarkCompileOnly 'com.vladsch.flexmark:flexmark-all:0.64.8'
 	// gherkin
 	gherkinCompileOnly 'io.cucumber:gherkin-utils:9.0.0'
 	gherkinCompileOnly 'org.slf4j:slf4j-api:2.0.0'