Try using autogen.sh as recommended in the ruby/ruby README

* The build fails on macOS in GitHub Actions currently:
  Run autoconf
  configure.ac:4182: warning: AC_C_BIGENDIAN should be used with AC_CONFIG_HEADERS

  Run ./configure --prefix=$HOME/.rubies/ruby-head --enable-shared --disable-install-doc --with-openssl-dir=$(brew --prefix openssl@1.1) --with-readline-dir=$(brew --prefix readline)
  configure: error: cannot find required auxiliary files: config.guess config.sub
  Error: Process completed with exit code 1.

Author: eregon

.github/workflows/build.yml

@@ -93,7 +93,7 @@ jobs:
     # Build
     - run: chmod 755 $HOME # https://github.com/actions/virtual-environments/issues/267
     - run: mkdir -p ~/.rubies
-    - run: autoconf
+    - run: ./autogen.sh
     - run: ./configure --prefix=$HOME/.rubies/ruby-${{ matrix.name }} --enable-shared --disable-install-doc
       if: startsWith(matrix.os, 'ubuntu')
     - run: ./configure --prefix=$HOME/.rubies/ruby-${{ matrix.name }} --enable-shared --disable-install-doc --with-openssl-dir=$(brew --prefix openssl@1.1) --with-readline-dir=$(brew --prefix readline)