Add compat annotation

Author: nickrobinson251

NEWS.md

@@ -31,7 +31,7 @@ Standard library changes
 
 * The methods of `mktemp` and `mktempdir` which take a function body to pass temporary paths to no longer throw errors if the path is already deleted when the function body returns ([#33091]).
 
-* A new `dropdims(f, args...; dims, kwargs...)` method computes the reduction `f` over the region described by `dims` and then drops those dimensions from the result ([#23500]).
+* A new `dropdims(f, args...; dims, kwargs...)` method computes the reduction `f` over the region described by `dims` and then drops those dimensions from the result ([#33130]).
 
 #### Libdl
 

base/abstractarraymath.jl

@@ -111,6 +111,9 @@ julia> dropdims(sum, abs2, a, dims=2)
   57.0
   94.0
 ```
+
+!!! compat "Julia 1.4"
+    This function requires at least Julia 1.4.
 """
 dropdims(f, args...; dims, kwargs...) = _dropdims(f(args...; kwargs..., dims=dims), dims)