fix bumpversion config

Bumpversion was failing because incorrect quote type was specified. This apparently was no problem for earlier, more lenient, bumpversion versions.

.bumpversion.cfg

@@ -1,12 +1,12 @@
 [bumpversion]
-current_version = 1.0.0
+current_version = 1.1.0
 
 [comment]
 comment = The contents of this file cannot be merged with that of setup.cfg until https://github.com/c4urself/bump2version/issues/185 is resolved
 
 [bumpversion:file:dianna/__init__.py]
-search = __version__ = "{current_version}"
-replace = __version__ = "{new_version}"
+search = __version__ = '{current_version}'
+replace = __version__ = '{new_version}'
 
 [bumpversion:file:setup.cfg]
 search = version = {current_version}
@@ -17,5 +17,5 @@ search = version: "{current_version}"
 replace = version: "{new_version}"
 
 [bumpversion:file:docs/conf.py]
-search = version = "{current_version}"
-replace = version = "{new_version}"
+search = version = '{current_version}'
+replace = version = '{new_version}'