Fix Solaris CI

The new target is called `x86_64-pc-solaris`, but `cross` doesn't
support that yet, so just use `sparcv9-sun-solaris`.

See the following issues for more info:
  rust-lang/rust#85098
  rust-lang/rust#82216

Signed-off-by: Joe Richey <joerichey@google.com>

.github/workflows/tests.yml

@@ -166,7 +166,7 @@ jobs:
     strategy:
       matrix:
         target: [
-          x86_64-sun-solaris,
+          sparcv9-sun-solaris,
           x86_64-unknown-netbsd,
         ]
     steps:
@@ -184,7 +184,7 @@ jobs:
           tar -C /tmp -xzf /tmp/binaries.tar.gz
           mv /tmp/cross ~/.cargo/bin
       - name: Build Tests
-        run: cross test --no-run --target=${{ matrix.target }} --features=std
+        run: cross test --target=${{ matrix.target }} --features=std
 
   web-tests:
     name: Web tests