LSTM-Model - Validation Accuracy is not changing
From the documentation:
inputs: A 3D tensor with shape [batch, timesteps, feature].
Are you saying that you want 1 input and 1 feature, but you want to output 100 neurons? I would consider adding more timesteps.
train_X = train_X.reshape(train_X.shape[0],10,1)
test_X = test_X.reshape(test_X.shape[0],10,1)

Also, I wouldn't add regularization to a ReLU activation without batch normalization. Actually, I probably would use dropout instead of regularization. Consider that with regularization many ReLU neurons may die.