Update Polynomials compat to include v4 (#507)

* Update Polynomials compat to v4

* Bump version to 0.7.9

Author: jishnub

Project.toml

@@ -1,6 +1,6 @@
 name = "DSP"
 uuid = "717857b8-e6f2-59f4-9121-6e50c889abd2"
-version = "0.7.8"
+version = "0.7.9"
 
 [deps]
 Compat = "34da2185-b29b-5c13-b0c7-acf172513d20"
@@ -18,7 +18,7 @@ Compat = "3.14, 4.1"
 FFTW = "1.1"
 IterTools = "1"
 OffsetArrays = "0.11, 1"
-Polynomials = "2, 3.0"
+Polynomials = "2, 3.0, 4"
 Reexport = "0.2, 1.0"
 SpecialFunctions = "0.8, 0.9, 0.10, 1.0, 2.0"
 julia = "1"