Try only on stable

Author: threema-donat

.github/workflows/ci.yml

@@ -38,31 +38,37 @@ jobs:
             args: -- -D clippy::all
             cache: {}
             components: "clippy"
+            only-on-stable: true
           - name: "Clippy (openssl feature)"
             cmd: clippy
             args: --no-default-features --features openssl -- -D clippy::all
             cache: {}
             components: "clippy"
+            only-on-stable: true
           - name: "Formatting"
             cmd: fmt
             args: -- --check
             cache: {}
             components: "rustfmt"
+            only-on-stable: false
           - name: "Unit Tests (all features)"
             cmd: test
             args: --all-features
             cache: { shared-key: "tests" }
             components: ''
+            only-on-stable: false
           - name: "Unit Tests (openssl feature)"
             cmd: test
             args: --no-default-features --features openssl
             cache: { shared-key: "tests-openssl" }
             components: ''
+            only-on-stable: false
     env:
       RUST_BACKTRACE: full
       RUSTC_WRAPPER: sccache
       SCCACHE_CACHE_SIZE: 1G
       SCCACHE_GHA_ENABLED: "true"
+    if: (matrix.cargo.only-on-stable == 'false') || (matrix.cargo.only-on-stable == 'true' && matrix.rust == 'stable')
     steps:
       # Checkout code
       - name: "Git checkout"