fix: casing of GET for PSR compat (#451)

Author: bshaffer

src/CachedKeySet.php

@@ -146,7 +146,7 @@ private function keyIdExists(string $keyId): bool
             if ($this->rateLimitExceeded()) {
                 return false;
             }
-            $request = $this->httpFactory->createRequest('get', $this->jwksUri);
+            $request = $this->httpFactory->createRequest('GET', $this->jwksUri);
             $jwksResponse = $this->httpClient->sendRequest($request);
             $jwks = (string) $jwksResponse->getBody();
             $this->keySet = JWK::parseKeySet(json_decode($jwks, true), $this->defaultAlg);

tests/CachedKeySetTest.php

@@ -325,7 +325,7 @@ private function getMockHttpFactory(int $timesCalled = 1)
     {
         $request = $this->prophesize('Psr\Http\Message\RequestInterface');
         $factory = $this->prophesize(RequestFactoryInterface::class);
-        $factory->createRequest('get', $this->testJwksUri)
+        $factory->createRequest('GET', $this->testJwksUri)
             ->shouldBeCalledTimes($timesCalled)
             ->willReturn($request->reveal());