Remove rpmforge URL that no longer exists

Let's try without updating git to a newer version. If it doesn't
work, I'll use a different rpmforge URL.

Merge pull request #560 from rstudio/node-v18.18.2

Node v18.18.2

Commit new generated files

The output changed slightly due to typescript upgrade (I think)

Merge pull request #527 from rstudio/v1.5.19-rc

V1.5.19 RC

Use same cmake version for centos7 as ubuntu18.04

Merge pull request #501 from rstudio/joe/bugfix/sockjs-jsonp-errors

Fix jsonp-polling unresponsiveness (similar to #499)

Use centos7 builder instead of centos6

Bump version to 1.5.15

Merge pull request #445 from rstudio/joe/misc/node-v12-18-0

Node v12.18.0

Merge pull request #432 from rstudio/joe/misc/node-v12-15-0

Update Node to v12.15.0