set GEN_COMPLETIONS to 1 in github workflows

.github/workflows/ci.yml

@@ -37,6 +37,8 @@ jobs:
         with:
           command: build
           args: --target ${{ matrix.target }}
+        env:
+          GEN_COMPLETIONS: 1
 
   clippy:
     name: clippy

.github/workflows/release.yml

@@ -94,6 +94,8 @@ jobs:
         uses: actions-rs/cargo@v1
         with:
           command: build
+        env:
+          GEN_COMPLETIONS: 1
 
       - name: Find generated completions
         run: |