fixed by:

Don't warn unused evidence of empty interface (in 2.13.14)
scala/scala#10692

Author: mzuehlke

modules/core/src/main/scala/org/scalasteward/core/data/Resolver.scala

@@ -59,7 +59,6 @@ object Resolver {
   val mavenCentral: MavenRepository =
     MavenRepository("public", "https://repo1.maven.org/maven2/", None, Nil)
 
-  @annotation.nowarn("cat=unused-locals")
   implicit val resolverCodec: Codec[Resolver] = {
     implicit val customConfig: Configuration = Configuration.default.withDefaults
     deriveConfiguredCodec

modules/core/src/main/scala/org/scalasteward/core/data/Scope.scala

@@ -49,7 +49,6 @@ object Scope {
         f(fa.value, lb)
     }
 
-  @annotation.nowarn("cat=unused-params")
   implicit def scopeCodec[A: Decoder: Encoder]: Codec[Scope[A]] =
     deriveCodec
 

modules/core/src/main/scala/org/scalasteward/core/forge/bitbucketserver/Json.scala

@@ -98,7 +98,6 @@ object Json {
   implicit val defaultReviewerDecoder: Decoder[DefaultReviewer] = deriveDecoder
   implicit val linkDecoder: Decoder[Link] = deriveDecoder
   implicit val newPREncoder: Encoder[NewPR] = deriveEncoder
-  @annotation.nowarn("cat=unused-params")
   implicit def pageDecoder[A: Decoder]: Decoder[Page[A]] = deriveDecoder
   implicit val prDecoder: Decoder[PR] = deriveDecoder
   implicit val projectCodec: Codec[Project] = deriveCodec