Update GitHub Actions workflows. (#741)

This PR was automatically generated by the
update-workflows-ecosystem-providers workflow in the pulumi/ci-mgmt
repo, from commit 76affe0b55f0a1271b352387b7ffe2c132a95826.

Author: pulumi-bot

.github/workflows/main-post-build.yml

@@ -60,6 +60,8 @@ jobs:
           COVERAGE_OUTPUT_DIR: ${{ runner.temp }}/cov
       - name: Summarize Provider Coverage Results
         run: cat ${{ env.COVERAGE_OUTPUT_DIR }}/shortSummary.txt
+        env:
+          COVERAGE_OUTPUT_DIR: ${{ runner.temp }}/cov
       - name: Upload coverage data to S3
         run: >-
           summaryName="${PROVIDER}_summary_$(date +"%Y-%m-%d_%H-%M-%S").json"