chore: Use Xcode 26.1 and iOS 26.1 on CI

[itaybre]

Test Xcode 26.1 and iOS 26.1 beta for CI

Given how unstable iOS 26.0 has been recently, let's try using iOS 26.1 beta

#skip-changelog

Closes #6468

[codecov]

❌ 2 Tests Failed:

Tests completed	Failed	Passed	Skipped
4015	2	4013	28

View the top 3 failed test(s) by shortest run time

SentryTests.SentryANRTrackerV2Tests::testFullyBlockingFollowedByFullyBlocking_BothReported

Stack Traces | 0s run time

.../Integrations/ANR/SentryANRTrackerV2Tests.swift:276 - Asynchronous wait failed: Exceeded timeout of 10 seconds, with unfulfilled expectations: "Test Delegate ANR Detection".

iOS_Swift_UITests.LaunchUITests::testCaptureError

Stack Traces | 0s run time

.../iOS-Swift/iOS-Swift-UITests/LaunchUITests.swift:39 - Failed to Error Domain=com.apple.dt.XCTest.XCTFuture Code=1000 "Timed out while evaluating UI query." UserInfo={NSLocalizedDescription=Timed out while evaluating UI query.}: Timed out while evaluating UI query.

iOS_Swift_UITests.LaunchUITests::testCheckTotalFrames

Stack Traces | 0s run time

.../iOS-Swift/iOS-Swift-UITests/LaunchUITests.swift:78 - Failed to Error Domain=com.apple.dt.XCTest.XCTFuture Code=1000 "Timed out while evaluating UI query." UserInfo={NSLocalizedDescription=Timed out while evaluating UI query.}: Timed out while evaluating UI query.

View the full list of 1 ❄️ flaky test(s)

SentryTests.SentryHttpTransportFlushIntegrationTests::testFlush_CallingFlushDirectlyAfterCapture_Flushes

Flake rate in main: 15.38% (Passed 11 times, Failed 2 times)

Stack Traces | 0s run time

.../SentryTests/Networking/SentryHttpTransportFlushIntegrationTests.swift:67 - XCTAssertEqual failed: ("1") is not equal to ("0")

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[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1218.96 ms	1252.65 ms	33.69 ms
Size	23.75 KiB	1021.48 KiB	997.73 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
aff3b66	1229.53 ms	1263.08 ms	33.55 ms
570f725	1206.00 ms	1238.96 ms	32.96 ms
2481950	1221.04 ms	1248.98 ms	27.94 ms
d3f650a	1225.45 ms	1241.86 ms	16.41 ms
07f6759	1232.98 ms	1267.59 ms	34.61 ms
1fecbb8	1242.78 ms	1265.40 ms	22.62 ms
6e99155	1223.96 ms	1249.25 ms	25.29 ms
fc05805	1220.63 ms	1252.16 ms	31.54 ms
0e9c5ae	1226.10 ms	1254.14 ms	28.04 ms
397b9c9	1230.23 ms	1249.29 ms	19.06 ms

App size

Revision	Plain	With Sentry	Diff
aff3b66	23.75 KiB	978.53 KiB	954.78 KiB
570f725	23.74 KiB	913.38 KiB	889.63 KiB
2481950	23.74 KiB	872.74 KiB	849.00 KiB
d3f650a	23.75 KiB	902.48 KiB	878.73 KiB
07f6759	23.75 KiB	997.26 KiB	973.52 KiB
1fecbb8	23.75 KiB	969.28 KiB	945.53 KiB
6e99155	23.75 KiB	963.18 KiB	939.43 KiB
fc05805	23.75 KiB	908.02 KiB	884.27 KiB
0e9c5ae	23.75 KiB	969.29 KiB	945.54 KiB
397b9c9	23.75 KiB	959.44 KiB	935.70 KiB