fix(scala): target Java 8 bytecode for fory-scala

[KarasevRob]

Why?

fory-scala Java sources are compiled with JDK 25 during release, producing Java 25 bytecode

What does this PR do?

Set the Java target to Java 8:

Compile / javacOptions ++= Seq("--release", "8")

Analogue to fory-json-scala

Related issues

• Fixes #3940

Does this PR introduce any user-facing change?

Fixes fory-scala compatibility with supported older JDKs.

• Does this PR introduce any public API change?
• Does this PR introduce any binary protocol compatibility change?

Benchmark

Not applicable.

[pjfanning]

lgtm

The .scala source files should still be Java 8 compatible - because the Scala compiler still targets Java 8 (unless you bump to Scala 3.8+ for the compiler)

The .java source files in fory-scala need this setting in order not to target the java version associated with the javac compiler used at build time.

[pjfanning]

Oddly foryJsonScala has the release setting but not foryScala.

Existing:

lazy val foryJsonScala = Project(id = "fory-json-scala", base = file("fory-json-scala"))
  .settings(commonSettings)
  .settings(
    name := "fory-json-scala",
    Compile / javacOptions ++= Seq("--release", "8"),