Skip broken test on v1.6 (#779)

* skip broken test on v1.6

* limit broken test to v1.7+

Author: jishnub

test/ReadmeTest.jl

@@ -107,16 +107,14 @@ using ApproxFun, SpecialFunctions, LinearAlgebra, Test
         #                     [ones(∂(d));0.];tolerance=1E-10)      # First four entries of rhs are
         #
 
-
-
-        QR = qr([Dirichlet(d);Laplacian()+100I])
-                @time ApproxFun.resizedata!(QR,:,4000)
-                @time u = \(QR,
-                                [ones(∂(d));0.];tolerance=1E-7)
-
-
-        @test u(0.1,1.) ≈ 1.0
-        @test ≈(u(0.1,0.2),-0.02768276827514463;atol=1E-8)
+        # this is broken on v1.6 (on BandedArrays < v0.16.16), so we skip on errors
+        if VERSION >= v"1.7"
+            QR = qr([Dirichlet(d);Laplacian()+100I])
+            @time ApproxFun.resizedata!(QR,:,4000)
+            @time u = \(QR, [ones(∂(d)); 0.]; tolerance=1E-7)
+            @test u(0.1,1.) ≈ 1.0
+            @test ≈(u(0.1,0.2),-0.02768276827514463;atol=1E-8)
+        end
     end
 
     # @testset "BigFloat" begin