Modify the pyprojetc.toml (possibly incorrectly)

Hatch uses hatchling as the underlying build system.

With older versions of hatchling the metadata is out of date with the
expected metadata for pypi (something to do with the license file -- I'm
not entirely sure what).

The way to build the dist with hatch/hatchling:

```
hatch build
```

You can check the Metadata version with:

```
tar -xzf dist/axelrod-*.tar.gz
cat axelrod-*/PKG-INFO | grep "Metadata-Version"
```

THIS SHOULD give you:

```
Metadata-Version: 2.4
```

Once that's done, assuming the auth is set up correctly you publish with

```
hatch publish
```

While I was fixing all this I was changing the pyproject.toml file.

We should open an issue to possibly put the license file back in
and also document the release process (essentially putting some of the
information I'm writing here).

For other projects of mine I have setup a publish worklow so that github
actions takes care of this. We could look in to doing that as well.

Author: drvinceknight

pyproject.toml

@@ -1,13 +1,12 @@
 [build-system]
-requires = ["hatchling"]
+requires = ["hatchling>=1.18.0"]
 build-backend = "hatchling.build"
 
 [project]
 name = "Axelrod"
 dynamic = ["version"]
 description = "Reproduce the Axelrod iterated prisoners dilemma tournament"
 readme = "README.rst"
-license = {file = "LICENSE.txt"}
 requires-python = ">=3.6"
 authors = [
     { name = "Vince Knight", email = "[email protected]" },