Fix path separators in build-msi.sh for Windows compatibility #757

Job	Run time
generate-build-number	3s
helm-chart-deploy	19s
home-docker-image-deploy	9m 35s
e2e-docker-image-deploy	9m 41s
isolated-vm-docker-image-deploy	8m 15s
nginx-docker-image-deploy	7m 4s
test-server-docker-image-deploy	9m 33s
status-page-docker-image-deploy	9m 35s
otel-collector-docker-image-deploy	1m 5s
admin-dashboard-docker-image-deploy	9m 39s
fluent-ingest-docker-image-deploy	9m 32s
haraka-docker-image-deploy	4m 33s
incoming-request-ingest-docker-image-deploy	9m 28s
open-telemetry-ingest-docker-image-deploy	9m 27s
probe-docker-image-deploy	9m 26s
probe-ingest-docker-image-deploy	9m 26s
accounts-docker-image-deploy	9m 29s
test-docker-image-deploy	1m 26s
app-docker-image-deploy	9m 24s
copilot-docker-image-deploy	9m 12s
dashboard-docker-image-deploy	8m 26s
docs-docker-image-deploy	7m 52s
llm-docker-image-deploy	5m 46s
publish-npm-packages	1m 7s
worker-docker-image-deploy	5m 13s
workflow-docker-image-deploy	4m 43s
api-reference-docker-image-deploy	2m 22s
test-e2e-release-saas	1s
test-e2e-release-self-hosted	1s
github-release	1s
infrastructure-agent-deploy	1s
	3h 1m 45s

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