Unable to import scikit-learn modules

### Describe the bug

Multiple imports unable to be imported within the imblearn and scikit-learn package.  Since there is no imblearn github repo, posting here.  Using scikit-learn version 1.1.2 and imbalanced-learn 0.9.1

Error:
ImportError                               Traceback (most recent call last)
<ipython-input-21-72be5dca49c0> in <module>
      2 from sklearn.pipeline import Pipeline
      3 from sklearn.model_selection import cross_val_score
----> 4 from sklearn.model_selection import RepeatedStratigiedKfold
      5 
      6 from imblearn.over_sampling import SMOTE

ImportError: cannot import name 'RepeatedStratigiedKfold' from 'sklearn.model_selection' (c:\python38\lib\site-packages\sklearn\model_selection\__init__.py)

Code:

```
from sklearn.tree import DecisionTreeClassifier
from sklearn.pipeline import Pipeline
from sklearn.model_selection import cross_val_score
from sklearn.model_selection import RepeatedStratigiedKfold

from imblearn.over_sampling import SMOTE

steps = [('over',SMOTE(), ('model', DecisionTreeClassifier()))]
pipeline = Pipeline(steps=steps)

data = cars.drop(['class'],1).squeeze()
target = cars[['class']].squeeze()

cv = RepeatedStratigiedKfold(n_splits=5, n_repeats=2, random_state=42)
scores = cross_val_score(pipeline, data, target, scoring='roc_auc',cv=cv, n_jobs=-1)

```
----------------------------------------------------------------------------------------------
Second error pasted here:

---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
<ipython-input-19-a163f13e4e3c> in <module>
----> 1 from imblearn.over_sampling import SMOTE, RandomUnderSampler
      2 
      3 def SMOTE_oversample(df, dep_var):
      4 
      5     data = df.drop([str(dep_var)],1).squeeze()

ImportError: cannot import name 'RandomUnderSampler' from 'imblearn.over_sampling' (C:\Users\benno\AppData\Roaming\Python\Python38\site-packages\imblearn\over_sampling\__init__.py)

With the following code:

```
from imblearn.over_sampling import SMOTE, RandomUnderSampler

def SMOTE_oversample(df, dep_var):

    data = df.drop([str(dep_var)],1).squeeze()
    target = df[[str(dep_var)]].squeeze()

    oversample = SMOTE()

    data, target = oversample.fit_resample(data, target)
    
    return data, target

data, target = SMOTE_oversample(cars, 'class')

```
What is going on in the code that is preventing these imports?

Python: 3.8.9
Scikit-learn: 1.1.2
Imblearn: 0.9.1
Environment: Jupyter Notebook

### Steps/Code to Reproduce

```
from sklearn.tree import DecisionTreeClassifier
from sklearn.pipeline import Pipeline
from sklearn.model_selection import cross_val_score
from sklearn.model_selection import RepeatedStratigiedKfold

from imblearn.over_sampling import SMOTE

steps = [('over',SMOTE(), ('model', DecisionTreeClassifier()))]
pipeline = Pipeline(steps=steps)

data = cars.drop(['class'],1).squeeze()
target = cars[['class']].squeeze()

cv = RepeatedStratigiedKfold(n_splits=5, n_repeats=2, random_state=42)
scores = cross_val_score(pipeline, data, target, scoring='roc_auc',cv=cv, n_jobs=-1)

```

### Expected Results

Expected to import correctly

### Actual Results

Error:
ImportError                               Traceback (most recent call last)
<ipython-input-21-72be5dca49c0> in <module>
      2 from sklearn.pipeline import Pipeline
      3 from sklearn.model_selection import cross_val_score
----> 4 from sklearn.model_selection import RepeatedStratigiedKfold
      5 
      6 from imblearn.over_sampling import SMOTE

ImportError: cannot import name 'RepeatedStratigiedKfold' from 'sklearn.model_selection' (c:\python38\lib\site-packages\sklearn\model_selection\__init__.py)

### Versions

```shell
Python: 3.8.9
Scikit-learn: 1.1.2
Imblearn: 0.9.1
Environment: Jupyter Notebook
```

COMMENT:
For the first issue, spelling is [RepeatedStratifiedKFold](https://scikit-learn.org/stable/modules/generated/sklearn.model_selection.RepeatedStratifiedKFold.html) i.e:

```python
from sklearn.model_selection import RepeatedStratifiedKFold
```

As for the second error, [RandomUnderSampler](https://imbalanced-learn.org/stable/references/generated/imblearn.under_sampling.RandomUnderSampler.html?highlight=randomundersampler#imblearn.under_sampling.RandomUnderSampler) is in `imblearn.under_sampling`:

```python
from imblearn.under_sampling import RandomUnderSampler
```

Labels: Bug, Needs Triage