Add AV1 and HEVC image encoding (#997)

Author: yosifkit

Dockerfile.template

@@ -22,6 +22,10 @@ RUN set -eux; \
 	apt-get install -y --no-install-recommends \
 # Ghostscript is required for rendering PDF previews
 		ghostscript \
+# pull in AV1 & HEVC image encoding (and not just decoding)
+# https://github.com/docker-library/wordpress/issues/996
+		libheif-plugin-aomenc \
+		libheif-plugin-x265 \
 	; \
 	rm -rf /var/lib/apt/lists/*
 {{ ) end -}}