Update local ruby version to 2.7.6. (#280)

kaibolay · web-flow · commit d99970830a29 · 2022-09-09T14:04:37.000-04:00
Also set ruby version for `asdf`.
diff --git a/.ruby-version b/.ruby-version
@@ -1 +1 @@
-2.6.3
+2.7.6
diff --git a/.tool-versions b/.tool-versions
@@ -0,0 +1 @@
+ruby 2.7.6
