CompatHelper: bump compat for "ApproxFun" to "0.13" (#149)

* CompatHelper: bump compat for "ApproxFun" to "0.13"

* Update Project.toml

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Sheehan Olver <solver@mac.com>

Author: github-actions[bot]

Project.toml

@@ -1,6 +1,6 @@
 name = "SingularIntegralEquations"
 uuid = "e094c991-5a90-5477-8896-c1e4c9552a1a"
-version = "0.6.8"
+version = "0.6.9"
 
 [deps]
 ApproxFun = "28f2ccd6-bb30-5033-b560-165f7b14dc2f"
@@ -18,7 +18,7 @@ SpecialFunctions = "276daf66-3868-5448-9aa4-cd146d93841b"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
-ApproxFun = "0.11.8, 0.12"
+ApproxFun = "0.11.8, 0.12, 0.13"
 ApproxFunBase = "0.2.3, 0.3, 0.4.4, 0.5"
 ApproxFunFourier = "0.2"
 ApproxFunOrthogonalPolynomials = "0.3, 0.4"