Update libzim to 8.2.1 for release 0.3 (#56)

Makefile

@@ -33,11 +33,11 @@ build/lib/liblzma.so :
 
 build/lib/libz.a :
  	# Version not yet available in dev.kiwix.org
-	wget -N https://zlib.net/zlib-1.2.13.tar.gz
-	tar xf zlib-1.2.13.tar.gz
-	cd zlib-1.2.13 ; emconfigure ./configure --prefix=`pwd`/../build
-	cd zlib-1.2.13 ; emmake make
-	cd zlib-1.2.13 ; emmake make install
+	wget -N https://zlib.net/zlib-1.3.tar.gz
+	tar xf zlib-1.3.tar.gz
+	cd zlib-1.3 ; emconfigure ./configure --prefix=`pwd`/../build
+	cd zlib-1.3 ; emmake make
+	cd zlib-1.3 ; emmake make install
 
 build/lib/libzstd.a :
 	# Origin: https://github.com/facebook/zstd/releases/download/v1.4.4/zstd-1.4.4.tar.gz 
@@ -69,13 +69,13 @@ build/lib/libxapian.a : build/lib/libz.a
 
 build/lib/libzim.a : build/lib/liblzma.so build/lib/libz.a build/lib/libzstd.a build/lib/libicudata.so build/lib/libxapian.a
 	# Origin: wget -N --content-disposition https://github.com/openzim/libzim/archive/7.2.2.tar.gz
-	[ ! -f libzim-*.tar.xz ] && wget -N https://download.openzim.org/release/libzim/libzim-8.2.0.tar.xz || true
-	tar xf libzim-8.2.0.tar.xz
+	[ ! -f libzim-*.tar.xz ] && wget -N https://download.openzim.org/release/libzim/libzim-8.2.1.tar.xz || true
+	tar xf libzim-8.2.1.tar.xz
 	# It's no use trying to compile examples
-	sed -i -e "s/^subdir('examples')//" libzim-8.2.0/meson.build
-	cd libzim-8.2.0; PKG_CONFIG_PATH=/src/build/lib/pkgconfig meson --prefix=`pwd`/../build --cross-file=../emscripten-crosscompile.ini . build -DUSE_MMAP=false
-	cd libzim-8.2.0; ninja -C build
-	cd libzim-8.2.0; ninja -C build install
+	sed -i -e "s/^subdir('examples')//" libzim-8.2.1/meson.build
+	cd libzim-8.2.1; PKG_CONFIG_PATH=/src/build/lib/pkgconfig meson --prefix=`pwd`/../build --cross-file=../emscripten-crosscompile.ini . build -DUSE_MMAP=false
+	cd libzim-8.2.1; ninja -C build
+	cd libzim-8.2.1; ninja -C build install
 
 # Development WASM version for testing with WORKERFS and NODEFS, completely unoptimized
 libzim-wasm.dev.js: libzim_bindings.cpp prejs_file_api.js postjs_file_api.js