Fix as per @edwardneal's suggestion

Author: benrr101

src/Microsoft.Data.SqlClient/tests/tools/Microsoft.Data.SqlClient.TestUtilities/Fixtures/CertificateFixtureBase.cs

@@ -86,8 +86,22 @@ protected X509Certificate2 CreateCertificate(string subjectName, IEnumerable<str
             // This is to ensure that it's imported into the certificate stores with its private key.
             using (X509Certificate2 ephemeral = request.CreateSelfSigned(notBefore, notAfter))
             {
-                return X509CertificateLoader.LoadPkcs12(ephemeral.Export(X509ContentType.Pkcs12, password), password,
-                    X509KeyStorageFlags.PersistKeySet | X509KeyStorageFlags.Exportable, new Pkcs12LoaderLimits(Pkcs12LoaderLimits.Defaults) { PreserveStorageProvider = true, PreserveKeyName = true });
+                #if NET9_0_OR_GREATER
+                return X509CertificateLoader.LoadPkcs12(
+                    ephemeral.Export(X509ContentType.Pkcs12, password),
+                    password,
+                    X509KeyStorageFlags.PersistKeySet | X509KeyStorageFlags.Exportable,
+                    new Pkcs12LoaderLimits(Pkcs12LoaderLimits.Defaults) 
+                    {
+                        PreserveStorageProvider = true,
+                        PreserveKeyName = true
+                    });
+                #else
+                return X509Certificate2(
+                    ephemeral.Export(X509ContentType.Pkcs12, password),
+                    password,
+                    X509KeyStorageFlags.PersistKeySet | X509KeyStorageFlags.Exportable);
+                #endif
             }
 #else
             // The CertificateRequest API is available in .NET Core, but was only added to .NET Framework 4.7.2; it thus can't be used in the test projects.