Rename various references to master branch

README.md

diff --git a/README.md b/README.md
index 0df556d..9deb32c 100644
--- a/README.md
+++ b/README.md
@@ -1,9 +1,9 @@
 [![Linux CI Status](https://github.com/harfbuzz/harfbuzz/workflows/linux-ci/badge.svg)](https://github.com/harfbuzz/harfbuzz/workflows/linux-ci/badge.svg)
-[![CircleCI Build Status](https://circleci.com/gh/harfbuzz/harfbuzz/tree/master.svg?style=svg)](https://circleci.com/gh/harfbuzz/harfbuzz/tree/master)
+[![CircleCI Build Status](https://circleci.com/gh/harfbuzz/harfbuzz/tree/main.svg?style=svg)](https://circleci.com/gh/harfbuzz/harfbuzz/tree/main)
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-[![Codecov Code Coverage](https://codecov.io/gh/harfbuzz/harfbuzz/branch/master/graph/badge.svg)](https://codecov.io/gh/harfbuzz/harfbuzz)
+[![Codecov Code Coverage](https://codecov.io/gh/harfbuzz/harfbuzz/branch/main/graph/badge.svg)](https://codecov.io/gh/harfbuzz/harfbuzz)
 [![Coverals Code Coverage](https://img.shields.io/coveralls/harfbuzz/harfbuzz.svg)](https://coveralls.io/r/harfbuzz/harfbuzz)
 [![Packaging status](https://repology.org/badge/tiny-repos/harfbuzz.svg)](https://repology.org/project/harfbuzz/versions)
 [ABI Tracker](http://abi-laboratory.pro/tracker/timeline/harfbuzz/)