Update version

nnabla_rl/__init__.py

@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-__version__ = '0.15.0.dev1'
+__version__ = '0.15.0'
 
 from nnabla_rl.logger import enable_logging, disable_logging  # noqa
 from nnabla_rl.scopes import eval_scope, is_eval_scope  # noqa