Update scala-compiler, scala-library, ... to 2.12.19 (#3414)

## About this PR
📦 Updates 
* [org.scala-lang:scala-compiler](https://github.com/scala/scala)
* [org.scala-lang:scala-library](https://github.com/scala/scala)
* [org.scala-lang:scala-reflect](https://github.com/scala/scala)

 from `2.12.18` to `2.12.19`

📜 [GitHub Release
Notes](https://github.com/scala/scala/releases/tag/v2.12.19) - [Version
Diff](scala/scala@v2.12.18...v2.12.19)

## Usage
✅ **Please merge!**

I'll automatically update this PR to resolve conflicts as long as you
don't change it yourself.

If you'd like to skip this version, you can just close this PR. If you
have any feedback, just mention me in the comments below.

Configure Scala Steward for your repository with a
[`.scala-steward.conf`](https://github.com/scala-steward-org/scala-steward/blob/b83aae55d9dd000548c3b3c9b63d79636e7b3c8b/docs/repo-specific-configuration.md)
file.

_Have a fantastic day writing Scala!_

<details>
<summary>⚙ Adjust future updates</summary>

Add this to your `.scala-steward.conf` file to ignore future updates of
this dependency:
```
updates.ignore = [ { groupId = "org.scala-lang" } ]
```
Or, add this to slow down future updates of this dependency:
```
dependencyOverrides = [{
  pullRequests = { frequency = "30 days" },
  dependency = { groupId = "org.scala-lang" }
}]
```
</details>

<sup>
labels: library-update
</sup>

airspec/build.sbt

@@ -13,7 +13,7 @@ addCommandAlias(
 // Reload build.sbt on changes
 Global / onChangedBuildSource := ReloadOnSourceChanges
 
-val SCALA_2_12          = "2.12.18"
+val SCALA_2_12          = "2.12.19"
 val SCALA_2_13          = "2.13.12"
 val SCALA_3             = "3.3.2"
 val targetScalaVersions = SCALA_3 :: SCALA_2_13 :: SCALA_2_12 :: Nil
@@ -130,8 +130,7 @@ def excludePomDependency(excludes: Seq[String]) = { node: XmlNode =>
   }).transform(node).head
 }
 
-/**
-  * AirSpec build definitions.
+/** AirSpec build definitions.
   *
   * To make AirSpec a standalone library without any cyclic project references, AirSpec embeds the source code of
   * airframe-log, di, surface, etc.

build.sbt

@@ -1,7 +1,7 @@
 import scalajsbundler.JSDOMNodeJSEnv
 import xerial.sbt.pack.PackPlugin.{projectSettings, publishPackArchiveTgz}
 
-val SCALA_2_12          = "2.12.18"
+val SCALA_2_12          = "2.12.19"
 val SCALA_2_13          = "2.13.12"
 val SCALA_3             = "3.3.2"
 val uptoScala2          = SCALA_2_13 :: SCALA_2_12 :: Nil

sbt-airframe/build.sbt

@@ -3,7 +3,7 @@ Global / onChangedBuildSource := ReloadOnSourceChanges
 
 val AIRFRAME_VERSION = sys.env.getOrElse("AIRFRAME_VERSION", "24.2.1")
 val AIRSPEC_VERSION  = sys.env.getOrElse("AIRSPEC_VERSION", "24.2.1")
-val SCALA_2_12       = "2.12.18"
+val SCALA_2_12       = "2.12.19"
 
 ThisBuild / organization := "org.wvlet.airframe"