Use checkout v3 for erlang < 20.3, and v4 for newer ones

actions/checkout@v4 updated from node16 to node20,
which requires a recent GLIBC 2.27 or 2.28,
however some old erlang container images include too old GLIBC

.github/workflows/ci.yml

@@ -9,12 +9,15 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        otp: ['19.3', '21.3', 24]
+        otp: ['19.3', '21.3', 25]
     runs-on: ubuntu-20.04
     container:
       image: erlang:${{ matrix.otp }}
     steps:
+    - uses: actions/checkout@v3
+      if: matrix.otp < '20.3'
     - uses: actions/checkout@v4
+      if: matrix.otp >= '20.3'
     - run: ./configure
     - run: make
     - run: rebar3 compile