Swift 6.0.3 for Linux (#1491)

Needed to unblock some upstream changed.

---------

Signed-off-by: Brentley Jones <[email protected]>

Author: brentleyjones

.bazelci/presubmit.yml

@@ -14,7 +14,7 @@ x_defaults:
     platform: ubuntu2004
     environment:
       CC: clang
-      SWIFT_VERSION: "5.10.1"
+      SWIFT_VERSION: "6.0.3"
       SWIFT_HOME: "$HOME/swift-$SWIFT_VERSION"
       PATH: "$SWIFT_HOME/usr/bin:$PATH"
   linux_common: &linux_common

.bcr/presubmit.yml

@@ -19,7 +19,7 @@ tasks:
     platform: ${{ platform }}
     environment:
       CC: "clang"
-      SWIFT_VERSION: "5.10.1"
+      SWIFT_VERSION: "6.0.3"
       SWIFT_HOME: "$HOME/swift-$SWIFT_VERSION"
       PATH: "$PATH:$SWIFT_HOME/usr/bin"
     shell_commands: *shell_commands