Use a MojoExecutionException constructor that exists in Maven 3.6.3

[slachiewicz]

MojoExecutionException(Throwable) arrived in Maven 3.9.0, so on the version <prerequisites>
declares, RenderDependenciesMojo.store raised NoSuchMethodError instead of the exception it
meant to throw. The reference is in released bytecode for 3.9.0, 3.10.0 and 3.11.0, not just in
source.

The message follows the sibling catch a few lines below rather than the bare e.getMessage()
the issue sketched, so the failure names the directory it could not create.

No unit test accompanies this

Not an omission. Compiled against the current <mavenVersion> (3.9.16) the constructor exists,
so any test of this branch passes with or without the fix. The only check that fails without it
is compiling against the baseline itself:

Verified: mvn -DmavenVersion=3.6.3 clean test-compile → BUILD SUCCESS; fails to compile on the parent commit

That check is #1683, which is red today for precisely this reason and goes green once this lands.
Merge this first — landing the guard first would turn master red.

Fixes #1682

_{Drafted with Claude — please verify}