Split examples & check minimum versions (#3370)

Currently, both cargo deny and our MSRV checks use Cargo.lock file which has unified features and versions across both the axum crates and all the examples. This can hide some issues as usually when someone adds an example, they might use cargo add which will silently update the dependency for the whole repository. Some compilation errors (like axum requiring [email protected] while it uses features from [email protected]) will then be hidden.

I don't think most users would ever need to use the minimal versions anyway so this is not as severe, but someone might run into compilation errors.

.github/workflows/CI.yml

@@ -24,6 +24,8 @@ jobs:
         save-if: ${{ github.ref == 'refs/heads/main' }}
     - name: Check
       run: cargo clippy --workspace --all-targets --all-features -- -D warnings
+    - name: Check
+      run: cargo clippy --manifest-path examples/Cargo.toml --workspace --all-targets --all-features -- -D warnings
     - name: rustfmt
       run: cargo fmt --all --check
 
@@ -92,6 +94,8 @@ jobs:
         save-if: ${{ github.ref == 'refs/heads/main' }}
     - name: Run tests
       run: cargo test --workspace --all-features --all-targets
+    - name: Test examples
+      run: cargo test --manifest-path examples/Cargo.toml --workspace --all-features --all-targets
 
   # some examples don't support our MSRV so we only test axum itself on our MSRV
   test-nightly:
@@ -129,8 +133,12 @@ jobs:
         save-if: ${{ github.ref == 'refs/heads/main' }}
     - name: Select minimal version
       run: cargo +nightly update -Z minimal-versions
-    - name: Fix up Cargo.lock
+    - name: Fix up Cargo.lock - crc32fast
       run: cargo +nightly update -p crc32fast --precise 1.1.1
+    - name: Fix up Cargo.lock - version_check
+      run : cargo +nightly update -p [email protected] --precise 0.1.4
+    - name: Fix up Cargo.lock - lazy_static
+      run: cargo +nightly update -p lazy_static --precise 1.1.0
     - name: Run tests
       run: >
         cargo +${{ env.MSRV }}