Restrict Polyester.jl to v0.7.16 (#2408)

* Restrict Polyester.jl

* use equal specifier to make Downgrade work

Author: ranocha

Project.toml

@@ -87,7 +87,7 @@ NLsolve = "4.5.1"
 Octavian = "0.3.28"
 OffsetArrays = "1.13"
 P4est = "0.4.12"
-Polyester = "0.7.16"
+Polyester = "=0.7.16"
 PrecompileTools = "1.2"
 Preferences = "1.4"
 Printf = "1"