fix: downgrade flexmark to 0.62.4

0.64.0 requires Java 11, so we can't move that high

Author: ckipp01

project/Dependencies.scala

@@ -10,7 +10,8 @@ object Dependencies {
   val `jackson-dataformat-yaml` =
     "com.fasterxml.jackson.dataformat" % "jackson-dataformat-yaml" % jacksonVersion
 
-  private val flexmarkVersion = "0.64.0"
+  // Freeze on 0.62.4 as 0.64.0 requires Java 11
+  private val flexmarkVersion = "0.62.4"
 
   val flexmarkDeps = Seq(
     "com.vladsch.flexmark" % "flexmark" % flexmarkVersion,