Update the symbols files to match that we're now on 2020.6

src/libostree/libostree-devel.sym

@@ -17,7 +17,7 @@
   Boston, MA 02111-1307, USA.
 ***/
 
-LIBOSTREE_2020.5 {
+LIBOSTREE_2020.6 {
 global:
   /* Add symbols here, and uncomment the bits in
    * Makefile-libostree.am to enable this too.

src/libostree/libostree-released.sym

@@ -593,6 +593,9 @@ global:
   ostree_sysroot_set_mount_namespace_in_use;
 } LIBOSTREE_2019.6;
 
+/* No new symbols in 2020.2 */
+/* No new symbols in 2020.3 */
+
 /* Add new symbols here.  Release commits should copy this section into -released.sym. */
 LIBOSTREE_2020.4 {
 global:
@@ -615,7 +618,7 @@ global:
   ostree_sign_summary;
 } LIBOSTREE_2020.1;
 
-/* No new symbols in 2020.2 */
+/* No new symbols in 2020.5 */
 
 /* NOTE: Only add more content here in release commits!  See the
  * comments at the top of this file.

tests/test-symbols.sh

@@ -66,7 +66,7 @@ echo 'ok documented symbols'
 
 # ONLY update this checksum in release commits!
 cat > released-sha256.txt <<EOF
-1f83814b9a785f9f612ee8f707dadb86d0dcbdc22603937575b7beefb26b50cc  ${released_syms}
+55f21380aa7f9ecc447a680b5c091692f2a0b98aa96ea00fba6aa6406aa69a5a  ${released_syms}
 EOF
 sha256sum -c released-sha256.txt