fixes enable_extension bug in postgresql_adapter

The use of quotations is required to install extensions with certain
characters in them (e.g. uuid-ossp).

removes CHANGELOG entry

Deemed unnecessary.
Merge pull request #9618 from manvsmachine/fix-postgres-enable-extension-error

Bugfix for enable_extension in postgresql_adapter.

The use of quotations is required to install extensions with certain
characters in them (e.g. uuid-ossp).