Exclude build artifacts from package via gitignore

[snekkalapudi]

Github issue: #7
Adding build/ to .gitignore

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This change is 

[k8s-ci-robot]

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[snekkalapudi]

/assign @abhi-g

[jlewi]

/assign @avdaredevil

[jlewi]

/assign @kwasi

[Bobgy]

Hi @snekkalapudi, it's not enough just excluding it, now build dir is required by this repo's consumers

[jlewi]

Looks like this PR should be closed.

[google-oss-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: snekkalapudi
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[avdaredevil]

/close

[google-oss-robot]

@avdaredevil: Closed this PR.

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/close

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