CompatHelper: bump compat for "FixedPointNumbers" to "0.8" (#76)

Co-authored-by: Robert Luke <[email protected]>

Author: github-actions[bot]

Project.toml

@@ -18,7 +18,7 @@ Unitful = "1986cc42-f94f-5a68-af5c-568840ba703d"
 Compat = "2, 3"
 DSP = "0.6.1"
 FFTW = "1.1.0"
-FixedPointNumbers = "0.6.1"
+FixedPointNumbers = "0.6.1, 0.7, 0.8"
 IntervalSets = "0.3.2"
 TreeViews = "0.3"
 Unitful = "0.17.0"