Fix trailing space on helm chart URL

[hasheddan]

Description of your changes

Removes a trailing space causing issues in CI when concatenating URL to branch.

Signed-off-by: hasheddan georgedanielmangum@gmail.com

I have:

• Read and followed Upbound's contribution process.
• Run make reviewable to ensure this PR is ready for review.
• Added backport release-x.y labels to auto-backport this PR, as appropriate.

How has this code been tested

Before:

🤖 (xgql-1) make -n helm.promote
echo `date +%H:%M:%S` [ .. ] promoting helm charts
aws s3 sync --only-show-errors s3://public-upbound.charts/master /tmp/tmp.QkzsL9avMr
if [ "public-upbound.releases/xgql" != "" ]; then \
	aws s3 sync --only-show-errors s3://public-upbound.releases/xgql/build/pub-bucket/v0.2.0-rc.0.48.gf01639a.dirty/charts /tmp/tmp.QkzsL9avMr; \
fi
/home/dan/code/github.com/upbound/xgql-1/.cache/tools/linux_x86_64/helm-v3.5.3 repo index --url https://charts.upbound.io /master /tmp/tmp.QkzsL9avMr
aws s3 sync --only-show-errors --delete /tmp/tmp.QkzsL9avMr s3://public-upbound.charts/master
aws s3 cp --only-show-errors --cache-control "private, max-age=0, no-transform" /tmp/tmp.QkzsL9avMr/index.yaml s3://public-upbound.charts/master/index.yaml
rm -fr /tmp/tmp.QkzsL9avMr
echo `date +%H:%M:%S` [ OK ] promoting helm charts

After:

🤖 (xgql-1) make -n helm.promote
echo `date +%H:%M:%S` [ .. ] promoting helm charts
aws s3 sync --only-show-errors s3://public-upbound.charts/master /tmp/tmp.doomB1IW3R
if [ "public-upbound.releases/xgql" != "" ]; then \
	aws s3 sync --only-show-errors s3://public-upbound.releases/xgql/build/whyyyy/v0.2.0-rc.0.49.g2898ba4.dirty/charts /tmp/tmp.doomB1IW3R; \
fi
/home/dan/code/github.com/upbound/xgql-1/.cache/tools/linux_x86_64/helm-v3.5.3 repo index --url https://charts.upbound.io/master /tmp/tmp.doomB1IW3R
aws s3 sync --only-show-errors --delete /tmp/tmp.doomB1IW3R s3://public-upbound.charts/master
aws s3 cp --only-show-errors --cache-control "private, max-age=0, no-transform" /tmp/tmp.doomB1IW3R/index.yaml s3://public-upbound.charts/master/index.yaml
rm -fr /tmp/tmp.doomB1IW3R
echo `date +%H:%M:%S` [ OK ] promoting helm charts

[thephred]

Oh my! Nice catch @hasheddan!