Merge pull request python-pillow#8661 from radarhere/no_giflib

Removed giflib as webp dependency

.github/workflows/wheels-dependencies.sh

@@ -45,7 +45,6 @@ OPENJPEG_VERSION=2.5.3
 XZ_VERSION=5.6.3
 TIFF_VERSION=4.6.0
 LCMS2_VERSION=2.16
-GIFLIB_VERSION=5.2.2
 ZLIB_NG_VERSION=2.2.3
 LIBWEBP_VERSION=1.5.0
 BZIP2_VERSION=1.0.8
@@ -135,18 +134,10 @@ function build {
     CFLAGS="$CFLAGS -O3 -DNDEBUG"
     if [[ -n "$IS_MACOS" ]]; then
         CFLAGS="$CFLAGS -Wl,-headerpad_max_install_names"
-    # For giflib 5.2.2
-    elif [ -n "$IS_ALPINE" ]; then
-        apk add imagemagick
-    elif [ -n "$SANITIZER" ]; then
-        apt-get install -y imagemagick
-    else
-        if [[ "$MB_ML_VER" == "_2_28" ]]; then
-            yum install -y epel-release
-        fi
-        yum install -y ImageMagick
     fi
-    build_libwebp
+    build_simple libwebp $LIBWEBP_VERSION \
+        https://storage.googleapis.com/downloads.webmproject.org/releases/webp tar.gz \
+        --enable-libwebpmux --enable-libwebpdemux
     CFLAGS=$ORIGINAL_CFLAGS
 
     build_brotli