automate cleaning up deprecated io/ioutil

.github/actions/copy-workflow-go/action.yml

@@ -46,6 +46,26 @@ runs:
             # We don't tidy, because the next step does that.
             # Separate commits also help with reviews.
             git commit -m "bump go.mod to Go $TARGET_VERSION and run go fix"
+
+            # As of Go 1.19 io/ioutil is deprecated
+            # We automate its upgrade here because it is quite a widely used package
+            while read file; do
+              sed -i 's/ioutil.NopCloser/io.NopCloser/' "${file}";
+              sed -i 's/ioutil.ReadAll/io.ReadAll/' "${file}";
+              # Skipping ReadDir replacement because it's a bit more complicated
+              # See https://pkg.go.dev/io/ioutil#ReadDir
+              # sed -i 's/ioutil.ReadDir/os.ReadDir/' "${file}";
+              sed -i 's/ioutil.ReadFile/os.ReadFile/' "${file}";
+              sed -i 's/ioutil.TempDir/os.MkdirTemp/' "${file}";
+              sed -i 's/ioutil.TempFile/os.CreateTemp/' "${file}";
+              sed -i 's/ioutil.WriteFile/os.WriteFile/' "${file}";
+            done <<< "$(find . -type f -name '*.go')"
+
+            go install golang.org/x/tools/cmd/goimports@b3b5c13b291f9653da6f31b95db100a2e26bd186 # v0.1.12
+            goimports -w .
+
+            git add .
+            git commit -m "stop using the deprecated io/ioutil package"
           fi
     - name: go mod tidy (on initial workflow deployment)
       if: ${{ env.INITIAL_WORKFLOW_DEPLOYMENT == 1 }}