lib: Fix Since versions for 2020.1

These had been added assuming 2019.7 would be the next version, but now
it's 2020 and there's been a release. In the case of
`OstreeCommitSizesEntry`, I'd forgotten to move it forward from 2019.5
to 2019.7 in the time between when I started working on the feature and
it landed.

src/libostree/ostree-core.c

@@ -2445,7 +2445,7 @@ G_DEFINE_BOXED_TYPE (OstreeCommitSizesEntry, ostree_commit_sizes_entry,
  * commit's "ostree.sizes" metadata.
  *
  * Returns: (transfer full) (nullable): a new #OstreeCommitSizesEntry
- * Since: 2019.7
+ * Since: 2020.1
  */
 OstreeCommitSizesEntry *
 ostree_commit_sizes_entry_new (const gchar      *checksum,
@@ -2471,7 +2471,7 @@ ostree_commit_sizes_entry_new (const gchar      *checksum,
  * Create a copy of the given @entry.
  *
  * Returns: (transfer full) (nullable): a new copy of @entry
- * Since: 2019.7
+ * Since: 2020.1
  */
 OstreeCommitSizesEntry *
 ostree_commit_sizes_entry_copy (const OstreeCommitSizesEntry *entry)
@@ -2490,7 +2490,7 @@ ostree_commit_sizes_entry_copy (const OstreeCommitSizesEntry *entry)
  *
  * Free given @entry.
  *
- * Since: 2019.7
+ * Since: 2020.1
  */
 void
 ostree_commit_sizes_entry_free (OstreeCommitSizesEntry *entry)
@@ -2572,7 +2572,7 @@ read_sizes_entry (GVariant                *entry,
  * the "ostree.sizes" metadata, a %G_IO_ERROR_NOT_FOUND error will be
  * returned.
  *
- * Since: 2019.7
+ * Since: 2020.1
  */
 gboolean
 ostree_commit_get_object_sizes (GVariant   *commit_variant,