CompatHelper: bump compat for "BlockArrays" to "0.15" (#58)

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

Author: github-actions[bot]

Project.toml

@@ -23,7 +23,7 @@ Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 AbstractFFTs = "0.5, 1"
 ApproxFunBase = "0.4"
 BandedMatrices = "0.16"
-BlockArrays = "0.14"
+BlockArrays = "0.14, 0.15"
 BlockBandedMatrices = "0.10"
 DomainSets = "0.4"
 FFTW = "1.1"