Rename test files since they are treated as modules anyway with their import statements.

diff --git a/test/create-wallet.test.mjs b/test/create-wallet.test.js
similarity index 100%
rename from test/create-wallet.test.mjs
rename to test/create-wallet.test.js

diff --git a/test/derive-accounts.test.mjs b/test/derive-accounts.test.js
similarity index 100%
rename from test/derive-accounts.test.mjs
rename to test/derive-accounts.test.js

diff --git a/test/import-wallet.test.mjs b/test/import-wallet.test.js
similarity index 100%
rename from test/import-wallet.test.mjs
rename to test/import-wallet.test.js

diff --git a/test/lock-unlock-wallet.mjs b/test/lock-unlock-wallet.js
similarity index 100%
rename from test/lock-unlock-wallet.mjs
rename to test/lock-unlock-wallet.js

diff --git a/test/manage-rolodex.mjs b/test/manage-rolodex.js
similarity index 100%
rename from test/manage-rolodex.mjs
rename to test/manage-rolodex.js

diff --git a/test/refresh-accounts.test.mjs b/test/refresh-accounts.test.js
similarity index 100%
rename from test/refresh-accounts.test.mjs
rename to test/refresh-accounts.test.js

diff --git a/test/sign-blocks.test.mjs b/test/sign-blocks.test.js
similarity index 100%
rename from test/sign-blocks.test.mjs
rename to test/sign-blocks.test.js

diff --git a/test/tools.test.mjs b/test/tools.test.js
similarity index 100%
rename from test/tools.test.mjs
rename to test/tools.test.js