Fix older CI for num-traits 0.2.19

Author: cuviper

Diff for: .github/workflows/ci.yaml

@@ -10,6 +10,8 @@ jobs:
       matrix:
         rust: [
           1.31.0, # MSRV
+          1.51.0,
+          1.60.0,
           stable,
           beta,
           nightly,

Diff for: 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

Diff for: 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