LAKITU: switch to using python 3.8 in the SDK

BUG=b/257113269
TEST=presubmit
RELEASE_NOTE=None

Change-Id: I266163ceedf15b0a851b1be8e326649e530579c4
Reviewed-on: https://cos-review.googlesource.com/c/third_party/overlays/chromiumos-overlay/+/42401
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Vaibhav Rustagi <vaibhavrustagi@google.com>
diff --git a/profiles/base/make.defaults b/profiles/base/make.defaults
index f3ad8eb..ed42c11 100644
--- a/profiles/base/make.defaults
+++ b/profiles/base/make.defaults
@@ -120,8 +120,8 @@
 
 # Mike Gilbert <floppym@gentoo.org> (15 May 2012)
 # Default target(s) for python-r1.eclass
-PYTHON_TARGETS="-python2_7 python3_6"
-PYTHON_SINGLE_TARGET="-python2_7 python3_6"
+PYTHON_TARGETS="-python2_7 -python3_6 python3_8"
+PYTHON_SINGLE_TARGET="-python2_7 -python3_6 python3_8"
 
 # MichaƂ Górny <mgorny@gentoo.org> (10 Aug 2013)
 # Moved from portage's make.globals.
diff --git a/profiles/targets/sdk/make.defaults b/profiles/targets/sdk/make.defaults
index a51cd9a..d8724313 100644
--- a/profiles/targets/sdk/make.defaults
+++ b/profiles/targets/sdk/make.defaults
@@ -62,8 +62,8 @@
 SYMLINK_LIB="yes"
 
 # Default target(s) for python-r1.eclass
-PYTHON_TARGETS="python3_6 python3_8"
-PYTHON_SINGLE_TARGET="python3_6"
+PYTHON_TARGETS="-python3_6 python3_8"
+PYTHON_SINGLE_TARGET="python3_8"
 
 # Use clang as the default compiler.
 CC=x86_64-pc-linux-gnu-clang