[skottie] Treat unknown effects as warnings

This used to be the case, but a recent change unintentionally switched
to errors.

TBR=
Change-Id: Ib92d2d04c667664921f47b48babdbe33e135b9ee
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/261179
Reviewed-by: Florin Malita <[email protected]>
Commit-Queue: Florin Malita <[email protected]>

Author: fmalita

modules/skottie/src/effects/Effects.cpp

@@ -83,7 +83,7 @@ EffectBuilder::EffectBuilderT EffectBuilder::findBuilder(const skjson::ObjectVal
     fBuilder->log(Logger::Level::kWarning, nullptr,
                   "Unsupported layer effect type: %d.", ParseDefault<int>(jeffect["ty"], -1));
 #else
-    fBuilder->log(Logger::Level::kError, &jeffect,
+    fBuilder->log(Logger::Level::kWarning, &jeffect,
                   "Unsupported layer effect: %s", mn ? mn->begin() : "(unknown)");
 #endif