Bump pygraphviz from 1.14 to 2.0

Bumps [pygraphviz](https://github.com/pygraphviz/pygraphviz) from 1.14 to 2.0.
- [Release notes](https://github.com/pygraphviz/pygraphviz/releases)
- [Changelog](https://github.com/pygraphviz/pygraphviz/blob/main/RELEASE.rst)
- [Commits](pygraphviz/pygraphviz@pygraphviz-1.14...pygraphviz-2.0)

---
updated-dependencies:
- dependency-name: pygraphviz
  dependency-version: '2.0'
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pyproject.toml

@@ -43,11 +43,11 @@ Repository = "https://github.com/pyiron/executorlib"
 [project.optional-dependencies]
 cache = ["h5py==3.16.0"]
 graph = [
-    "pygraphviz==1.14",
+    "pygraphviz==2.0",
     "networkx==3.6.1",
 ]
 graphnotebook = [
-    "pygraphviz==1.14",
+    "pygraphviz==2.0",
     "networkx==3.6.1",
     "ipython==9.9.0",
 ]
@@ -64,7 +64,7 @@ all = [
     "pysqa==0.4.3",
     "h5py==3.16.0",
     "pydantic==2.13.4",
-    "pygraphviz==1.14",
+    "pygraphviz==2.0",
     "networkx==3.6.1",
     "ipython==9.9.0",
 ]