semver-auto: remove labels first

Change the tasks order, so we clean semver labels first.
This avoids the case when the rebase failed, and we still have the old
label, and also the `semver:unknown`, which is confusing.

.github/workflows/semver-auto.yaml

@@ -6,6 +6,16 @@ jobs:
   go-apidiff:
     runs-on: ubuntu-latest
     steps:
+    - name: Remove the semver labels
+      uses: actions-ecosystem/action-remove-labels@2ce5d41b4b6aa8503e285553f75ed56e0a40bae0
+      with:
+        labels: |
+          semver:patch
+          semver:minor
+          semver:major
+          semver:unknown
+        github_token: ${{ secrets.GITHUB_TOKEN }}
+
     - uses: actions/checkout@v3
       with:
         fetch-depth: 0
@@ -27,16 +37,6 @@ jobs:
       with:
         go-version: '1'
 
-    - name: Remove the semver label
-      uses: actions-ecosystem/action-remove-labels@2ce5d41b4b6aa8503e285553f75ed56e0a40bae0
-      with:
-        labels: |
-          semver:patch
-          semver:minor
-          semver:major
-          semver:unknown
-        github_token: ${{ secrets.GITHUB_TOKEN }}
-
     - name: Checking Go API Compatibility
       id: go-apidiff
       uses: joelanford/go-apidiff@v0.7.0