Fix older CI for num-traits 0.2.19

.github/workflows/ci.yaml

@@ -8,7 +8,14 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        rust: [1.31.0, stable, beta, nightly]
+        rust: [
+          1.31.0, # MSRV
+          1.51.0,
+          1.60.0,
+          stable,
+          beta,
+          nightly,
+        ]
     steps:
       - uses: actions/checkout@v4
       - uses: actions/cache@v4

ci/rustup.sh

@@ -5,6 +5,6 @@
 set -ex
 
 ci=$(dirname $0)
-for version in 1.31.0 stable beta nightly; do
+for version in 1.31.0 1.51.0 1.60.0 stable beta nightly; do
     rustup run "$version" "$ci/test_full.sh"
 done

ci/test_full.sh

@@ -30,6 +30,12 @@ fi
 FEATURES=()
 echo "Testing supported features: ${FEATURES[*]}"
 
+cargo generate-lockfile
+
+# num-traits 0.2.19 started using dep: features, which requires 1.60 and is
+# otherwise ignored down to 1.51, but we need a manual downgrade before that.
+check_version 1.51 || cargo update -p num-traits --precise 0.2.18
+
 set -x
 
 # test the default