fix: use github.run_number for BUILD_VERSION in nightly workflow

Resolves npm version error in scheduled runs where github.event.number
is undefined, causing invalid version string "0.99."

Signed-off-by: Gavin Didrichsen <[email protected]>

Author: gavindidrichsen

.github/workflows/nightly.yml

@@ -62,7 +62,7 @@ jobs:
 
       - name: npm test
         env:
-          BUILD_VERSION: '0.99.${{ github.event.number }}'
+          BUILD_VERSION: 0.99.${{ github.run_number }}
           VSCODE_BUILD_VERBOSE: true
           DISPLAY: ':99.0'
         shell: pwsh
@@ -72,7 +72,7 @@ jobs:
       - name: vsce package
         if: runner.os == 'Linux'
         env:
-          BUILD_VERSION: '0.99.${{ github.event.number }}'
+          BUILD_VERSION: 0.99.${{ github.run_number }}
         shell: pwsh
         run: |
           invoke-psake -properties @{ packageVersion = $env:BUILD_VERSION } -tasklist bump