Revert to scala 2.12.12 due to scoverage issue with scala 2.12.13

Problem/Solution

The scoverage plugin has an issue due to a binary incompatibility introduced in scala 2.12.13
(see: scoverage/sbt-scoverage#319). It has been patched in the
plugin in scoverage/scalac-scoverage-plugin#306 which is currently
awaiting a release. However after updating our projects to scala 2.12.13, coverage is broken
and failing the CI builds. Downgrade to scala 2.12.12 until the scoverage plugin has been
published with the fix.

Differential Revision: https://phabricator.twitter.biz/D635917

Author: cacoco

.github/workflows/continuous-integration.yml

@@ -19,7 +19,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        scala: [2.12.13, 2.13.1]
+        scala: [2.12.12, 2.13.1]
         java: ['1.8', '1.11']
     runs-on: ubuntu-latest
     steps:

CHANGELOG.rst

@@ -22,6 +22,9 @@ Breaking API Changes
 Changed
 ~~~~~~~
 
+* finatra: Revert to scala version 2.12.12 due to https://github.com/scoverage/sbt-scoverage/issues/319
+  ``PHAB_ID=D635917``
+
 * finatra: Bump scala version to 2.12.13 ``PHAB_ID=D632567``
 
 * finatra: Move com.twitter.finatra.http.{jsonpatch,request} from the finatra/http-server project to

build.sbt

@@ -8,8 +8,8 @@ val releaseVersion = "21.3.0-SNAPSHOT"
 
 lazy val buildSettings = Seq(
   version := releaseVersion,
-  scalaVersion := "2.12.13",
-  crossScalaVersions := Seq("2.12.13", "2.13.1"),
+  scalaVersion := "2.12.12",
+  crossScalaVersions := Seq("2.12.12", "2.13.1"),
   scalaModuleInfo := scalaModuleInfo.value.map(_.withOverrideScalaVersion(true)),
   fork in Test := true, // We have to fork to get the JavaOptions
   javaOptions in Test ++= travisTestJavaOptions,