Meta: Update makem.sh, Makefile, test.yml

.github/workflows/test.yml

@@ -1,6 +1,9 @@
 # * test.yml --- Test Emacs packages using makem.sh on GitHub Actions
 
-# https://github.com/alphapapa/makem.sh
+# URL: https://github.com/alphapapa/makem.sh
+# Version: 0.2
+
+# * Commentary:
 
 # Based on Steve Purcell's examples at
 # <https://github.com/purcell/setup-emacs/blob/master/.github/workflows/test.yml>,
@@ -39,6 +42,7 @@ jobs:
       matrix:
         emacs_version:
           - 26.3
+          - 27.1
           - snapshot
     steps:
     - uses: purcell/setup-emacs@master
@@ -50,7 +54,7 @@ jobs:
     - name: Initialize sandbox
       run: |
         SANDBOX_DIR=$(mktemp -d) || exit 1
-        echo ::set-env name=SANDBOX_DIR::$SANDBOX_DIR
+        echo "SANDBOX_DIR=$SANDBOX_DIR" >> $GITHUB_ENV
         ./makem.sh -vv --sandbox=$SANDBOX_DIR --install-deps --install-linters
 
     # The "all" rule is not used, because it treats compilation warnings