Update swift-protobuf version and pin it to a strict version

The pinning ensures that our presubmit-check and all developers working
on Fuzzilli have a consistent version used for regenerating the
*.bp.swift files.

The non-exact version caused the GitHub run to fail as a newer
swift-protobuf version now resulted in diffs in the generated files.

Change-Id: I4edeae1a38e0b912a45e17b20b950066db4b24d4
Reviewed-on: https://chrome-internal-review.googlesource.com/c/v8/fuzzilli/+/9032256
Commit-Queue: Matthias Liedtke <mliedtke@google.com>
Auto-Submit: Matthias Liedtke <mliedtke@google.com>
Reviewed-by: Michael Achenbach <machenbach@google.com>

Author: Liedtke

Package.swift

@@ -25,7 +25,11 @@ let package = Package(
         .library(name: "Fuzzilli",targets: ["Fuzzilli"]),
     ],
     dependencies: [
-        .package(url: "https://github.com/apple/swift-protobuf.git", from: "1.31.0"),
+        // We use an exact version here as we also use this version to generate the .pb.swift to
+        // ensure that they are always regenerated with a consistent version. So this entry locks
+        // the version. It can be bumped arbitrarily, however, the generated files should be
+        // regenerated, whenever the version is bumped.
+        .package(url: "https://github.com/apple/swift-protobuf.git", exact: "1.35.0"),
         .package(
           url: "https://github.com/apple/swift-collections.git",
           .upToNextMinor(from: "1.2.0")