DOC: fix announce formtting
Master:

```
    Contributors
    ============

    A total of 143 people contributed patches to this release.  People with a
"+" by their names contributed a patch for the first time.

    * 3vts +
* A Brooks +
* Abbie Popa +
* Achmad Syarif Hidayatullah +
```

PR

```
Contributors
============

A total of 143 people contributed patches to this release.  People with a
"+" by their names contributed a patch for the first time.

* 3vts +
* A Brooks +
* Abbie Popa +
```

I think the offset computed by textwrap.dedent changed. With fstrings it's calculated after the values are interpolated. We want it to be computed on the templated version.