CI: Fix installation of defined SQLAlchemy version, bringing back SA13

The order of operations was wrong. So, previously, the process would
always install SQLAlchemy 1.4, skipping testing on SQLAlchemy 1.3.

.github/workflows/tests.yml

@@ -47,6 +47,9 @@ jobs:
           # Bootstrap environment.
           source bootstrap.sh
 
+          # Report about the test matrix slot.
+          echo "Invoking tests with CrateDB ${CRATEDB_VERSION} and SQLAlchemy ${SQLALCHEMY_VERSION}"
+
           # Invoke validation tasks.
           flake8 src bin
           coverage run bin/test -vv1

bootstrap.sh

@@ -65,6 +65,15 @@ function setup_package() {
     # Install package in editable mode.
     pip install --editable='.[sqlalchemy,test,doc]'
 
+    # Install designated SQLAlchemy version.
+    if [ -n "${SQLALCHEMY_VERSION}" ]; then
+      if [ "${SQLALCHEMY_VERSION}" = "latest" ]; then
+        pip install "sqlalchemy" --upgrade
+      else
+        pip install "sqlalchemy==${SQLALCHEMY_VERSION}"
+      fi
+    fi
+
 }
 
 function run_buildout() {

devtools/setup_ci.sh

@@ -10,20 +10,6 @@ function main() {
     echo "Environment variable 'CRATEDB_VERSION' needed"
     exit 1
   }
-  [ -z ${SQLALCHEMY_VERSION} ] && {
-    echo "Environment variable 'SQLALCHEMY_VERSION' needed"
-    exit 1
-  }
-
-  # Let's go.
-  echo "Invoking tests with CrateDB ${CRATEDB_VERSION} and SQLAlchemy ${SQLALCHEMY_VERSION}"
-
-  # Install designated SQLAlchemy version.
-  if [ ${SQLALCHEMY_VERSION} = "latest" ]; then
-    pip install "sqlalchemy" --upgrade
-  else
-    pip install "sqlalchemy==${SQLALCHEMY_VERSION}"
-  fi
 
   # Replace CrateDB version.
   if [ ${CRATEDB_VERSION} = "nightly" ]; then