Merge rust-bitcoin/rust-secp256k1#624: Fix broken stuff

567c39c7f1 Revert "WIP: Add toolchain matrix to job" (Tobin C. Harding)
e6643c083d CI: Pin dependencies for MSRV build ... properly (Tobin C. Harding)

Pull request description:

  Goodness me, I made a mess.

  Commit `0e0dcb7f CI: Pin dependencies required for MSRV build` is totally wrong, why did it get through CI?

  Fix broken stuff in the CI script by doing:

  - `serde_json` is not a dependency of `secp256k1`, remove the pinning
  - Put the pinning _before_ any call to `cargo`
  - Pin the transient dependency `wasm-bindgen-test`

  And then `Revert "WIP: Add toolchain matrix to job"`

  Fix: #626

ACKs for top commit:
  apoelstra:
    ACK 567c39c7f1

Tree-SHA512: f60a95e1c840e265dba1d10d2e87b970f1ebc5f01514ef9edaaf0475d833dbce15b8e715a6c53052786036b1dbbba73a2be0e470afd0d37320f540081c51c8e8

.github/workflows/rust.yml

@@ -105,16 +105,13 @@ jobs:
   WASM:
     name: WASM
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        toolchain: [stable, beta, nightly, 1.48.0]
     steps:
       - name: Checkout Crate
         uses: actions/checkout@v3
       - name: Install clang
         run: sudo apt-get install -y clang
       - name: Checkout Toolchain
-        uses: dtolnay/rust-toolchain@${{ matrix.toolchain }}
+        uses: dtolnay/rust-toolchain@stable
       - name: Running WASM tests
         env:
           DO_WASM: true

contrib/test.sh

@@ -13,19 +13,18 @@ if cargo --version | grep nightly; then
     NIGHTLY=true
 fi
 
+# Pin dependencies as required if we are using MSRV toolchain.
+if cargo --version | grep "1\.48"; then
+    cargo update -p wasm-bindgen-test --precise 0.3.34
+    cargo update -p serde --precise 1.0.156
+fi
+
 # Test if panic in C code aborts the process (either with a real panic or with SIGILL)
 cargo test -- --ignored --exact 'tests::test_panic_raw_ctx_should_terminate_abnormally' 2>&1 | tee /dev/stderr | grep "SIGILL\\|panicked at '\[libsecp256k1\]"
 
 # Make all cargo invocations verbose
 export CARGO_TERM_VERBOSE=true
 
-# Pin dependencies as required if we are using MSRV toolchain.
-if cargo --version | grep "1\.48"; then
-    # 1.0.157 uses syn 2.0 which requires edition 2021
-    cargo update -p serde_json --precise 1.0.99
-    cargo update -p serde --precise 1.0.156
-fi
-
 # Defaults / sanity checks
 cargo build --all
 cargo test --all