Dockerfile-release: add missing libwebp build/runtime dependency

The stb image backend (src/libs/image/CMakeLists.txt) does a
pkg_check_modules(WebP REQUIRED IMPORTED_TARGET libwebp), but
Dockerfile-release never installed libwebp-dev/libwebp, so the
release image build failed at the cmake configure step with
'Package libwebp not found'. Added both the Alpine build-time
(libwebp-dev) and runtime (libwebp) packages.

Dockerfile-release

@@ -22,6 +22,7 @@ ARG	BUILD_PACKAGES=" \
 	libpng-dev \
 	libtool \
 	libvorbis-dev \
+	libwebp-dev \
 	make \
 	onnxruntime-dev \
 	openjpeg-dev \
@@ -162,6 +163,7 @@ ARG	RUNTIME_PACKAGES=" \
 	libpng \
 	libpulse \
 	libvorbis \
+	libwebp \
 	libssl3 \
 	onnxruntime \
 	openjpeg \