Update MetaGraphsNext requirement from 0.5, 0.6, 0.7 to 0.5, 0.6, 0.7, 0.8

Updates the requirements on [MetaGraphsNext](https://github.com/JuliaGraphs/MetaGraphsNext.jl) to permit the latest version.
- [Release notes](https://github.com/JuliaGraphs/MetaGraphsNext.jl/releases)
- [Commits](https://github.com/JuliaGraphs/MetaGraphsNext.jl/commits/v0.8.0)

---
updated-dependencies:
- dependency-name: MetaGraphsNext
  dependency-version: 0.8.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

Project.toml

@@ -22,7 +22,7 @@ AbstractTrees = "0.4"
 DataFrames = "1"
 DelimitedFiles = "1"
 Graphs = "1"
-MetaGraphsNext = "0.5, 0.6, 0.7"
+MetaGraphsNext = "0.5, 0.6, 0.7, 0.8"
 MutableNamedTuples = "0.1"
 OrderedCollections = "1.4"
 SHA = "0.7, 1"