drm_hwcomposer: CI: Bump-up clang toolchain to v15

Address new clang-tidy findings, in most cases 'misc-const-correctness'
check was addressed by adding 'const' modifier, or in some cases changed
to 'auto' (where it's better for formatting).

Signed-off-by: Roman Stratiienko <r.stratiienko@gmail.com>
diff --git a/.ci/.gitlab-ci-checkcommit.sh b/.ci/.gitlab-ci-checkcommit.sh
index c6f7c4e..ff293a8 100755
--- a/.ci/.gitlab-ci-checkcommit.sh
+++ b/.ci/.gitlab-ci-checkcommit.sh
@@ -50,7 +50,7 @@
 		exit 1
 	fi
 
-	git show "$h" -- | clang-format-diff-14 -p 1 -style=file > /tmp/format-fixup.patch
+	git show "$h" -- | clang-format-diff-15 -p 1 -style=file > /tmp/format-fixup.patch
 	if [ -s  /tmp/format-fixup.patch ]; then
 		cat /tmp/format-fixup.patch >&2
 		exit 1
diff --git a/.ci/Makefile b/.ci/Makefile
index 581c6d9..88cde2e 100644
--- a/.ci/Makefile
+++ b/.ci/Makefile
@@ -2,8 +2,8 @@
 INCLUDE_DIRS := . ../libdrm/include/drm include ./.ci/android_headers ./tests/test_include
 SYSTEM_INCLUDE_DIRS := /usr/include/libdrm
 
-CLANG := clang++-14
-CLANG_TIDY := clang-tidy-14
+CLANG := clang++-15
+CLANG_TIDY := clang-tidy-15
 OUT_DIR := /tmp/drm_hwcomposer/build
 SRC_DIR := .