(maint) add clojure setup to github workflows

The latest ubuntu image no longer includes clojure/lein,
this commit adds a step for that inclusion to the linting
and PR testing workflows.

Author: steveax

.github/workflows/clojure-linting.yaml

@@ -15,6 +15,10 @@ jobs:
         with:
           distribution: temurin
           java-version: 17
+      - name: setup clojure
+        uses: DeLaGuardo/[email protected]
+        with:
+            lein: 2.11.2                  # Leiningen
       - name: checkout repo
         uses: actions/checkout@v2
       - name: install clj-kondo (this is quite fast)

.github/workflows/pr-testing.yaml

@@ -24,6 +24,10 @@ jobs:
         with:
           distribution: 'temurin'
           java-version: ${{ matrix.version }}
+      - name: setup clojure
+        uses: DeLaGuardo/[email protected]
+        with:
+            lein: 2.11.2                  # Leiningen
       - name: clojure tests
         run: lein test
         timeout-minutes: 30