Rename ci yaml file

Author: kateinoigakukun

.github/workflows/main.yml renamed to .github/workflows/build-toolchain.yml

@@ -1,4 +1,4 @@
-name: CI
+name: Build Toolchain
 
 on:
   push:

utils/webassembly/distribute-latest-toolchain.sh

@@ -2,7 +2,7 @@
 
 set -xe
 repository='swiftwasm/swift'
-workflow_name='main.yml'
+workflow_name='build-toolchain.yml'
 branch=$1
 channel=$2
 swift_source_dir="$(cd "$(dirname $0)/../.." && pwd)"