Raise compiler required for syn-codegen to 1.82

Required since version 2.12.0 of indexmap.

Author: dtolnay

.github/workflows/ci.yml

@@ -43,7 +43,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: [stable, beta, 1.68.0]
+        rust: [stable, beta, 1.82.0, 1.68.0]
         include:
           - rust: nightly
             components: rustc-dev
@@ -86,7 +86,8 @@ jobs:
       - run: cargo check ${{env.target}} --no-default-features --features 'full fold visit visit-mut parsing printing'
       - if: matrix.components == 'rustc-dev'
         run: cargo check --benches --all-features --release
-      - run: cargo check ${{env.target}} --manifest-path json/Cargo.toml --no-default-features
+      - if: matrix.rust != '1.68.0'
+        run: cargo check ${{env.target}} --manifest-path json/Cargo.toml --no-default-features
 
   examples:
     name: Examples