Bazel 7 fixes (#372)

## What?
* Use a newer @platforms repo
* Use default condition on select where needed

.bazelci/presubmit.yml

@@ -1,5 +1,5 @@
 ---
-bazel: 6.0.0
+bazel: 6.3.2
 
 buildifier:
   version: latest

.bazelversion

@@ -1 +1 @@
-6.3.1
+6.3.2

dotnet/private/tests/dependency_resolution/diamond_dependencies/d/BUILD.bazel

@@ -9,6 +9,9 @@ csharp_library(
     private_deps = select({
         "@rules_dotnet//dotnet:tfm_net6.0": ["@rules_dotnet_dev_nuget_packages//microsoft.netcore.app.ref"],
         "@rules_dotnet//dotnet:tfm_netstandard2.1": ["@rules_dotnet_dev_nuget_packages//netstandard.library.ref"],
+        # TODO: look into why this is needed in Bazel 7 but not 6
+        # The transition should be taking care of transitioning to a valid config for this select
+        "//conditions:default": [],
     }),
     target_frameworks = [
         "net6.0",

dotnet/repositories.bzl

@@ -35,6 +35,15 @@ def rules_dotnet_dependencies():
         url = "https://github.com/aspect-build/bazel-lib/releases/download/v1.29.2/bazel-lib-v1.29.2.tar.gz",
     )
 
+    http_archive(
+        name = "platforms",
+        urls = [
+            "https://mirror.bazel.build/github.com/bazelbuild/platforms/releases/download/0.0.7/platforms-0.0.7.tar.gz",
+            "https://github.com/bazelbuild/platforms/releases/download/0.0.7/platforms-0.0.7.tar.gz",
+        ],
+        sha256 = "3a561c99e7bdbe9173aa653fd579fe849f1d8d67395780ab4770b1f381431d51",
+    )
+
 ########
 # Remaining content of the file is only used to support toolchains.
 ########

examples/.bazelversion

@@ -1 +1 @@
-6.3.1
+6.3.2