Update StarAlgebras requirement to 0.2.1 (#138)

* Update StarAlgebras requirement to 0.2.1

Updates the requirements on [StarAlgebras](https://github.com/JuliaAlgebra/StarAlgebras.jl) to permit the latest version.
- [Release notes](https://github.com/JuliaAlgebra/StarAlgebras.jl/releases)
- [Commits](JuliaAlgebra/StarAlgebras.jl@v0.1.0...v0.2.1)

---
updated-dependencies:
- dependency-name: StarAlgebras
  dependency-version: 0.2.1
  dependency-type: direct:production
...

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

* v0.3

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Benoît Legat <benoit.legat@gmail.com>

Author: dependabot[bot]

Project.toml

@@ -20,14 +20,15 @@ StarAlgebras = "0c0c59c1-dc5f-42e9-9a8b-b5dc384a6cd1"
 [compat]
 DataStructures = "0.19"
 DynamicPolynomials = "0.5, 0.6"
-IntervalArithmetic = "0.20, 0.21, 0.22, 1" # Needs v0.20 for Julia v1.6 support
+IntervalArithmetic = "0.20, 0.21, 0.22, 1"
 JuMP = "1"
 MathOptInterface = "1"
 MultivariateBases = "0.2"
 MultivariateMoments = "0.4"
 MultivariatePolynomials = "0.5"
 MutableArithmetics = "1"
 SemialgebraicSets = "0.3"
+StarAlgebras = "0.3"
 julia = "1.6"
 
 [extras]