Fix the global Random.seed in runtests.jl (#2381)

Co-authored-by: Penelope Yong <[email protected]>

Author: mhauru

test/runtests.jl

@@ -1,10 +1,14 @@
 include("test_utils/SelectiveTests.jl")
 using .SelectiveTests: isincluded, parse_args
 using Pkg
+using Random: seed!
 using Test
 using TimerOutputs: TimerOutputs, @timeit
 import Turing
 
+# Fix the global Random.seed for reproducibility.
+seed!(23)
+
 include(pkgdir(Turing) * "/test/test_utils/models.jl")
 include(pkgdir(Turing) * "/test/test_utils/numerical_tests.jl")
 include(pkgdir(Turing) * "/test/test_utils/ad_utils.jl")