.github/workflows: lowercase github action names

Change-Id: I90a87b2bd9aaaed3022803506a9c34d0140c034d
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/411099
Reviewed-by: Suzy Mueller <[email protected]>

Author: hyangah

.github/workflows/release-nightly.yml

@@ -52,7 +52,7 @@ jobs:
         run: npm run unit-test
 
       - name: Run tests
-        uses: GabrielBB/xvfb-action@86d97bde4a65fe9b290c0b3fb92c2c4ed0e5302d
+        uses: gabrielbb/xvfb-action@86d97bde4a65fe9b290c0b3fb92c2c4ed0e5302d
         with:
           run: npm run test
         env:

.github/workflows/test-long-all.yml

@@ -52,7 +52,7 @@ jobs:
         run: npm run unit-test
 
       - name: Run tests
-        uses: GabrielBB/xvfb-action@86d97bde4a65fe9b290c0b3fb92c2c4ed0e5302d
+        uses: gabrielbb/xvfb-action@86d97bde4a65fe9b290c0b3fb92c2c4ed0e5302d
         with:
           run: npm run test
         env:

.github/workflows/test-long.yml

@@ -52,7 +52,7 @@ jobs:
         run: npm run unit-test
 
       - name: Run tests
-        uses: GabrielBB/xvfb-action@86d97bde4a65fe9b290c0b3fb92c2c4ed0e5302d
+        uses: gabrielbb/xvfb-action@86d97bde4a65fe9b290c0b3fb92c2c4ed0e5302d
         with:
           run: npm run test
         env:

.github/workflows/test-smoke.yml

@@ -49,7 +49,7 @@ jobs:
         run: npm run unit-test
 
       - name: Run tests
-        uses: GabrielBB/xvfb-action@86d97bde4a65fe9b290c0b3fb92c2c4ed0e5302d
+        uses: gabrielbb/xvfb-action@86d97bde4a65fe9b290c0b3fb92c2c4ed0e5302d
         with:
           run: npm run test
         env: