Use v2 of the Cargo feature resolver and make CI work with it

.github/workflows/CI.yml

@@ -2,7 +2,7 @@ name: CI
 
 env:
   CARGO_TERM_COLOR: always
-  MSRV: 1.56.0
+  MSRV: 1.56
 
 on:
   push:
@@ -113,6 +113,12 @@ jobs:
         command: update
         args: -Z minimal-versions
         toolchain: nightly
+    - name: Fix up Cargo.lock
+      uses: actions-rs/cargo@v1
+      with:
+        command: update
+        args: -p crc32fast --precise 1.1.1
+        toolchain: nightly
     - name: Run tests
       uses: actions-rs/cargo@v1
       with:
@@ -121,7 +127,6 @@ jobs:
           -p axum
           -p axum-extra
           -p axum-core
-          -p internal-minimal-versions
           --all-features
           --all-targets
           --locked

Cargo.toml

@@ -4,9 +4,5 @@ members = [
     "axum-core",
     "axum-extra",
     "axum-macros",
-
-    # internal crate used to bump the minimum versions we
-    # get for some dependencies which otherwise wouldn't build
-    # with `cargo +nightly update -Z minimal-versions`
-    "internal-minimal-versions",
 ]
+resolver = "2"

axum/Cargo.toml

@@ -56,7 +56,7 @@ multer = { version = "2.0.0", optional = true }
 serde_json = { version = "1.0", features = ["raw_value"], optional = true }
 serde_urlencoded = { version = "0.7", optional = true }
 sha-1 = { version = "0.10", optional = true }
-tokio-tungstenite = { version = "0.17", optional = true }
+tokio-tungstenite = { version = "0.17.2", optional = true }
 
 [dev-dependencies]
 anyhow = "1.0"

examples/Cargo.toml

@@ -1,3 +1,4 @@
 [workspace]
 members = ["*"]
 exclude = ["target"]
+resolver = "2"