fix version typo (#855)

Author: lzchen

CHANGELOG.md

@@ -3,8 +3,8 @@
 ## Unreleased
 
 ## 0.7.7
-Released 2020-02-03
-- Update `azure` module
+Released 2020-02-04
+- Updated `azure` module
   ([#837](https://github.com/census-instrumentation/opencensus-python/pull/837),
    [#845](https://github.com/census-instrumentation/opencensus-python/pull/845),
    [#848](https://github.com/census-instrumentation/opencensus-python/pull/848),

opencensus/common/version/__init__.py

@@ -12,4 +12,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-__version__ = '0.7.6'
+__version__ = '0.7.7'