Fixes suggested by VSCode (#226)

Author: blegat

test/comparison.jl

@@ -83,18 +83,18 @@
         Mod.@polyvar x
         # Polynomial of multiple terms
         p = x + x^2
-        @test nothing != p
-        @test p != nothing
+        @test nothing !== p
+        @test p !== nothing
         @test Dict{Int,Int}() != p
-        @test p != Dict{Int,Int}()
+        @test p !== Dict{Int,Int}()
         # Polynomial of one term
         p = x + x^2 - x
-        @test p != nothing
-        @test p != Dict{Int,Int}()
+        @test p !== nothing
+        @test p !== Dict{Int,Int}()
         # Polynomial of no term
         # See https://github.com/blegat/MultivariatePolynomials.jl/issues/22
         p = x - x
-        @test p != nothing
-        @test p != Dict{Int,Int}()
+        @test p !== nothing
+        @test p !== Dict{Int,Int}()
     end
 end

test/rational.jl

@@ -18,7 +18,7 @@
     #@test iszero(zero(RationalPoly{true, Float64, Int}))
     #@test typeof(x / 2) == Term{true, Float64}
     #@test typeof((x + x^2) / 3.0) == Polynomial{true, Float64}
-    @test nothing != x / (x^2 + 1)
+    @test nothing !== x / (x^2 + 1)
     @test (x^2 + 1) / (2x) != nothing
     @test Dict{Int,Int}() != x / (x^2 + 1)
     @test (x^2 + 1) / (2x) != Dict{Int,Int}()