Move benchmarks to a separate crate in the workspace

This should make CI work on 1.41.1 even though criterion doesn't compile
on that version.

Author: meithecatte

Cargo.toml

@@ -23,16 +23,9 @@ optional = true
 [features]
 std = []
 
-[dev-dependencies]
-criterion = "0.3"
-
-[[bench]]
-name = "from_iterator"
-harness = false
-path = "benches/from_iterator.rs"
-
 [workspace]
 members = [
     "enumflags_derive",
     "test_suite",
+    "benchmarks",
 ]

benchmarks/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "enumflags-benchmarks"
+version = "0.0.0"
+publish = false
+
+[dependencies.enumflags2]
+path = "../"
+
+[dev-dependencies]
+criterion = "0.3"
+
+[[bench]]
+name = "from_iterator"
+harness = false
+path = "from_iterator.rs"