lib: Minor versioning related fixes

Fix/add the `Since` marker to the new static delta APIs, and update the
symbol versioning templates/comments.

src/libostree/libostree-devel.sym

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

src/libostree/libostree-released.sym

@@ -620,6 +620,8 @@ global:
 
 /* No new symbols in 2020.5 */
 
+/* No new symbols in 2020.6 */
+
 /* NOTE: Only add more content here in release commits!  See the
  * comments at the top of this file.
  */

src/libostree/ostree-repo-static-delta-core.c

@@ -317,6 +317,8 @@ _ostree_repo_static_delta_verify_signature (OstreeRepo       *self,
  * The directory must be named with the form "FROM-TO", where both are
  * checksums, and it must contain a file named "superblock", along with at least
  * one part.
+ *
+ * Since: 2020.7
  */
 gboolean
 ostree_repo_static_delta_execute_offline_with_signature (OstreeRepo   *self,
@@ -1082,7 +1084,7 @@ _ostree_repo_static_delta_dump (OstreeRepo                    *self,
  * Returns: TRUE if the signature of static delta file is valid using the
  * signature engine provided, FALSE otherwise.
  *
- * Since: 2020.1
+ * Since: 2020.7
  */
 gboolean
 ostree_repo_static_delta_verify_signature (OstreeRepo       *self,

tests/test-symbols.sh

@@ -66,7 +66,7 @@ echo 'ok documented symbols'
 
 # ONLY update this checksum in release commits!
 cat > released-sha256.txt <<EOF
-55f21380aa7f9ecc447a680b5c091692f2a0b98aa96ea00fba6aa6406aa69a5a  ${released_syms}
+f341345be2da30ab8043ac3d555f75edaae25aaad9f81a933fb4e33a47fe7cc4  ${released_syms}
 EOF
 sha256sum -c released-sha256.txt