Remove remaining "master" branch references

There are some remaining "master" branch references

Before this PR, grep -r -l -E "bootstrap/blob/master" *:

dist/js/bootstrap.esm.js
dist/js/bootstrap.bundle.js
dist/js/bootstrap.bundle.min.js.map
dist/js/bootstrap.bundle.js.map
dist/js/bootstrap.esm.js.map
dist/js/bootstrap.js
dist/js/bootstrap.esm.min.js.map
dist/js/bootstrap.js.map
dist/js/bootstrap.min.js.map
js/dist/offcanvas.js
js/dist/modal.js.map
js/dist/offcanvas.js.map
js/dist/modal.js

With this PR, after running npm run release, the command grep -r -l -E "bootstrap/blob/master" * doesn't return anything.