Update V8 version after branch cut

TBR=machenbach@chromium.org

Change-Id: I3ea2bb7431ee9c5834e9ca58cf88511fb719a0cf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2442623Reviewed-by: Michael Hablich <hablich@chromium.org>
Commit-Queue: Michael Hablich <hablich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70258}

include/v8-version.h

@@ -9,7 +9,7 @@
 // NOTE these macros are used by some of the tool scripts and the build
 // system so their names cannot be changed without changing the scripts.
 #define V8_MAJOR_VERSION 8
-#define V8_MINOR_VERSION 7
+#define V8_MINOR_VERSION 8
 #define V8_BUILD_NUMBER 0
 #define V8_PATCH_LEVEL 0