chore(ci): fix the apidiff action (googleapis#837)

* chore(ci): replace accidentally removed install steps

* force go version 1.18.3

* fix apidiff target

* try upload/download of baseline

* upload package diff file

* remove diff upload

* add retention-days

.github/workflows/apidiff.yaml

@@ -11,8 +11,23 @@ jobs:
     - uses: actions/checkout@v3
       with:
         ref: main
+    - uses: actions/setup-go@v3
+      with:
+        go-version: '1.18.3'
+    - name: Install latest apidiff
+      run: go install golang.org/x/exp/cmd/apidiff@latest
     - name: Create Go package baseline
-      run: apidiff -w pkg.main google.golang.org/genproto
+      run: apidiff -w pkg.main ./...
+    - name: Upload baseline package data
+      uses: actions/upload-artifact@v3
+      with:
+        name: pkg.main
+        path: pkg.main
+        retention-days: 1
     - uses: actions/checkout@v3
+    - name: Download baseline package data
+      uses: actions/download-artifact@v3
+      with:
+        name: pkg.main
     - name: Compare regenerated code to baseline
-      run: apidiff -incompatible pkg.main google.golang.org/genproto > diff.txt && cat diff.txt && ! [ -s diff.txt ]
+      run: apidiff -incompatible pkg.main ./... > diff.txt && cat diff.txt && ! [ -s diff.txt ]