Fix testAsync, test_stdlibsamples and testSrcPEP420Packages with Python 3.10 (#11017)

* tests: make testAsync work with Python 3.10

The test would previously yield "DeprecationWarning: There is no current
event loop".

* tests: fix test_stdlibsamples with Python 3.10

by accounting for the move from collections to collections.abc.

* tests: fix testSrcPEP420Packages with Python 3.10

Before this change, the test would yield "mypy.ini: No [mypy] section in
config file" because of the double closing bracket.

This is caused by a fix for https://bugs.python.org/issue38741 that is
included in Python 3.10:
python/cpython@1cc6769

Author: sbraz

mypyc/test-data/run-misc.test

@@ -2,6 +2,7 @@
 
 [case testAsync]
 import asyncio
+import sys
 
 async def h() -> int:
     return 1
@@ -13,17 +14,27 @@ async def g() -> int:
 async def f() -> int:
     return await g()
 
-loop = asyncio.get_event_loop()
-result = loop.run_until_complete(f())
+# sys.version_info >= (3, 7) fails with
+# error: Unsupported left operand type for >= ("Tuple[int, int, int, str, int]")
+if sys.version_info[0] >= 3 and sys.version_info[1] >= 7:
+    result = asyncio.run(f())
+else:
+    loop = asyncio.get_event_loop()
+    result = loop.run_until_complete(f())
 assert result == 1
 
 [typing fixtures/typing-full.pyi]
 
 [file driver.py]
 from native import f
 import asyncio
-loop = asyncio.get_event_loop()
-result = loop.run_until_complete(f())
+import sys
+
+if sys.version_info >= (3, 7):
+    result = asyncio.run(f())
+else:
+    loop = asyncio.get_event_loop()
+    result = loop.run_until_complete(f())
 assert result == 1
 
 [case testMaybeUninitVar]

test-data/stdlib-samples/3.2/random.py

@@ -41,7 +41,7 @@
 from math import log as _log, exp as _exp, pi as _pi, e as _e, ceil as _ceil
 from math import sqrt as _sqrt, acos as _acos, cos as _cos, sin as _sin
 from os import urandom as _urandom
-from collections import Set as _Set, Sequence as _Sequence
+from collections.abc import Set as _Set, Sequence as _Sequence
 from hashlib import sha512 as _sha512
 
 from typing import (

test-data/unit/cmdline.test

@@ -791,7 +791,7 @@ c.py:2: error: Argument 1 to "bar" has incompatible type "str"; expected "int"
 [case testSrcPEP420Packages]
 # cmd: mypy -p anamespace --namespace-packages
 [file mypy.ini]
-\[mypy]]
+\[mypy]
 mypy_path = src
 [file src/setup.cfg]
 [file src/anamespace/foo/__init__.py]