fix: drop Swift 5.10 from spi.yml, restore android platform

Swift 5.10 builds fail across all platforms because the codebase
uses Swift 6 strict concurrency (@preconcurrency, Sendable, etc.).
Advertising 5.10 support created misleading red builds on SPI.

Android is a valid SPI platform — restored with swift_versions: ["6.0"]
using the correct plural key (was incorrectly singular in v1.4.1).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: vkuttyp

.spi.yml

@@ -1,6 +1,5 @@
 version: 1
 swift_versions:
-  - "5.10"
   - "6.0"
   - "6.1"
   - "6.2"
@@ -17,3 +16,6 @@ builder:
       linux_packages:
         - libsqlite3-dev
         - pkg-config
+    - platform: android
+      swift_versions:
+        - "6.0"